Oh, I wasn't using those percentages as a predictor of being bumped up. Those were my personal thresholds of when it would be appropriate for a player to play up a level. If they didn't meet those parameters, I think they should refrain from wasting partners'/opponents' time by playing up a level.
Generally, I won't disagree with you on these matters as you have so much more experience than me. However, I think I will disagree with you on this one, just slightly
The year I got bumped up from 3.5 to 4.0, my win rate wasn't that high at all, as it never is actually. I played up at the 4.0 level too with a very low win rate at that level, 11%. Maybe some of my partners were not happy playing with me, but it was invaluable for me in increasing my confidence level, learning to play better, and getting to know the 4.0 players in our area. Also, although our team won the 3.5 nationals (40+ I think it was, no?), I did not actually go to the Nationals tourney with you, so that wasn't a factor in my bump up either. And my post-season record wasn't anything to brag about, 66% win rate there. My overall win rate at 3.5 rated matches was 70%, both 40+ and 18+.
And just for kicks, my overall 3.5 level games won rate was 59%.
My standards are a bit lower than yours certainly. I do believe it is important to play up, in moderation, at any level. At the end, if the goal is to advance one's game and become a more rounded tennis player; not necessarily winning championships or tourneys. If the objective is to focus on post-season wins, then I have to agree with your approach, which is where you and I differ