I like both periods equally, but severally people here at the HTF have expressed a wish that Universal would release the sets in reverse order. So, you're not alone.
The Beav wasn't in high school during Season Six. He had just graduated junior high (or Middle School, or whatever "Mayfield USA" called it in 1962-1963).
"We now stand in the vestibule of life".
In "Ward's day", he "Stood on the 'Threshold of Tomorrow'".
The series, without mentioning it, played around with Wally and the Beaver's status in school the last season.
In Season Five, Beaver was in sixth grade and Wally was a senior in high school (he started high school the second season.)
All of a sudden, in Season Six, Beaver's in eighth grade (don't tell me he skipped a grade!) and Wally's STILL a senior in high school (and don't tell me he flunked!)
They held Wally back, of course, so that he wouldn't go off to college and not be in the show.
If there had been a seventh season, I don't know what they would have done. But there wasn't.
There's some interesting "playing around" with the school grades of Beaver during Season 2 as well.
The first S.2 show -- "Beaver's Poem" -- features several (very smoothly done) edits that were integrated into the episode. Each edit (or "dub") revolves around the school "grade" that Beaver was supposed to be in at the time. The original filmed dialogue has the words "second grade" spoken by various cast members throughout the episode. But, on each of these occasions, the words "third grade" have been seamlessly dubbed into the script by the actors at a later date.
One small glitch on mine: At the very end of "Cleaning up Beaver" when Beaver is talking to Larry, sometimes the disk will freeze at the part where Larry says he gets lonley by himself to the part where Beaver decides to comb his hair as part of the deal he made with Wally. (Just before the end credits.) I wiped it off with a clean lint-free cloth (center to edge) and sometimes that same spot every time will play ok sometimes not. Not sure of returning it for fear of other disks from Universal having similar problems. (This is a common problem with Universal and double-sided disks.) But if I get another freeze up, it might have to go back. We shall see. Always take a dry lint-free cloth and clean the disks first. Sometimes all it takes is a little bit of smudge to get on them, and they can skip. I also noticed on the disk very very faint scuff marks inside of the coating, but there is one part where there looks like there might be a little centimeter of gunk that I can't get off with the cloth.