I was gen 11, then retired at level 32 (I fucked my build up and got 2 looms) so then at gen 12 I was "done retiring for good" I hit level 33 and was only 1 or 2 million xp more when they had the double XP sunday. I got another loom from donating, and decided to retire at 33 for 3 more looms and got a few million xp that sunday. So now I'm gen 13 and only 5.5 million from being at level 33 again.
If I retired every time I was 31 instead of at 32 and 33 that would be 3 extra gen's I lost out on, so I'd be at the XP cap if I knew I'd be retiring up til this point, oh well, live and learn