Pre-requisites to Season 6?

Nice way of putting it.

So that should be the plan A rather than planning to intentionally never watch or back watch 2/3 of the episodes.

There are various reasons why viewing a show in order isn’t possible or desirable and that doesn’t mean it’s not worth watching. The viewer should just be aware of the downsides. It’s true that a new viewer might want to start watching at the point the show is in when they discover it. It is indeed a unique experience to watch the ending of a show at the time it airs and it’s fun to be part of that. The original poster didn’t and doesn’t have to mention the reason for bookending.

I believe especially with a show that’s more serial than procedural like this one a viewer will get the best experience watching in order. So that should be the plan A rather than planning to intentionally never watch or back watch 2/3 of the episodes.

I mostly agree you on this and it is my own personal preference to watch all seasons and each characters development. It's why I went and bought the Blu Rays for each season to re-watch when ever I like. It does help in gaining a better appreciation for all of the characters current positions. However, recaps can be subject to bias depending on who edited them as they may not be official and taking an objective look at the situation, i.e. someone who may want to experience the final episodes at the same time as everyone else and enjoy the hype surrounding the countdown to the final finale:

1. We are currently experiencing the first broadcast of the final episodes and that is an experience in itself that is nice to be part of. Is there enough time for anyone trying to catch up with four and half seasons of the show before they miss out on that spoiler free experience?
   


2. Note the half season is the Phantom Zone plot. All anyone needs to know for the moment is Kara spent time in the phantom zone. It is possible to come back and watch the detail later.
   


3. I said previously that “Missing the previous seasons would be like hearing a punchline without the experience of the lead up to it.” That’s ok if anyone does not want to miss the hype surrounding the final episodes. Although if the alternative is chosen, to watch all the way through first; avoiding spoilers will be hard, especially when random YouTube thumbnails pop up.
   


4. All anyone needs to know is: Some characters left, there are some new characters (relative to only seeing season one), follow what they are doing at this moment with an understanding that you can catch up later if you so choose.
   

Over here in Ireland I had a similar experience with ‘Smallvile’ although through no fault of my own. Channel 4/E4 were terrible at scheduling it. Starting seasons with no advertisement; unannounced episodes aired at random times (E4's VideoPlus codes never worked properly either) to fit around their flagship show ‘Big Brother’ etc. There were times when I only discovered an entire season of episodes had aired after the fact. They did advertise the Final episode , I watched it and enjoyed it. I was able to follow it despite not seeing much before. I only eventually saw the full series a few years later when I decided to buy the complete 10 season DVD set.

Since Lena was introduced in season two the poster who only watched season one wouldn’t know who she is. There would be no context for her character or her relationships to others if one jumped from season one to six. Same with Brainy who didn’t appear until season three. I guess it depends on how much the viewer cares about wondering, where did this character go or how did this character get here. There are characters in season one who leave in later seasons so a viewer might wonder what happened. Not to mention what happened with the DEO. Recap’s of past seasons episodes exist online and those might be helpful if a person wanted to bookend.

The bookend approach to watching Supergirl is flawed. The best episodes are from season 1,2 and 3. Season 2 is my favorite season because they introduce Chris Wood to the show. The chemistry between Melissa and Chris is amazing and hasn't been seen since Tracy and Hepburn. After you viewed those seasons than I would highly recommend dry martini's while watching season 4 and 5. Then I would skip season 6 until the finale.

July 20,1969 "Oh My God" "The Americans Are On The Moon"
Warren Zevon-Werewolves Of London-Video

Thank you all for your keen insights. Very helpful, really appreciate it!

Personally, no I don't think it makes sense to jump from season 1 to season 6. Season 1 was on a different network and the show changed a lot when the show moved networks. Imo it makes more sense to jump from season 2 at least to season 6.

[*]Lena appears to mirror Willow from 'Buffy the Vampire Slayer' (Btvs). Kara's best friend for most of the series. Then like Willow in the second last season a traumatic experience (season four finale) sends Lena down a path of evil. In both series Willow and Lena's souls are saved in the season finale. Then in the final season of Supergirl and Btvs both work to better themselves by taking a short time out in a different country and improve there magic skills throughout the season. I can't help but think the Lena is going to do something big in the last episode like Willow did in 'Chosen'

Since Lena was introduced in season two the poster who only watched season one wouldn’t know who she is. There would be no context for her character or her relationships to others if one jumped from season one to six. Same with Brainy who didn’t appear until season three. I guess it depends on how much the viewer cares about wondering, where did this character go or how did this character get here. There are characters in season one who leave in later seasons so a viewer might wonder what happened. Not to mention what happened with the DEO. Recap’s of past seasons episodes exist online and those might be helpful if a person wanted to bookend.

The answer, is really up to personal choice. I haven't seen anything in Season Six that drastically depends on you having watched all previous seasons to understand what is going on. However, if you watch Supergirl in this way you might lose out on gaining an appreciation for the development of each character.

A Few things to note:

1. First, Like any show with twentyish episodes per season there are mostly great memorable episodes along with occasionally some duds. This is the nature of any show with this many episodes and the few bad episodes are still better than a lot of other TV out there.
   


2. There is a lot of character evolution that created healthy and challenging debates in terms of modern society on this site and across the web. Some of these issues the topics were ahead of their time and very well handled (some may disagree with me as is their right). i.e. Alex coming out, gun ownership, Dreamer in season fives Reality Bytes.
   


3. Season six has a lot of payoffs for plotlines that have been background character development for years such as Alex's longing to adopt a child. Missing the previous seasons would be like hearing a punchline without the experience of the lead up to it.
   


4. Lena appears to mirror Willow from 'Buffy the Vampire Slayer' (Btvs). Kara's best friend for most of the series. Then like Willow in the second last season a traumatic experience (season four finale) sends Lena down a path of evil. In both series Willow and Lena's souls are saved in the season finale. Then in the final season of Supergirl and Btvs both work to better themselves by taking a short time out in a different country and improve there magic skills throughout the season. I can't help but think the Lena is going to do something big in the last episode like Willow did in 'Chosen'.
   


5. Various interpretations and reinterpretations (due to 'Crisis on Infinite Earths') of other DC Hero's and Villains. At least two of which have been reinterpreted for Superman and Lois.
   


6. The Crossovers.
   

I would not recommend the bookend approach. You’ll have no context for some of the character development, be wondering where some characters went and where some came from. I would recommend watching seasons 2-5 at least and in order. TBH your missing things if you don’t know what happened in some of the crossovers. Everything but one Batwoman episode of Crisis on Infinite Earths is on Netflix. Enjoy the ride.