Thanks all! Ai, I did not think of that the shorter lifestages will no longer experience every season. It might be a good thing though, like not all YA will be able to have a Summer wedding (at least not while still being fresh YAs), and not all children will meet Father Winter etc. I age them all up manually, so it would not be a problem allowing each lifestage a few more days, but if I double their length, it would mean that my population would take forever to grow up, hm, I must give this a thought...
Edit: Thinking for 5 seconds and I realize this is not a problem, haha. I grow up the entire community one year on New Year's Eve (or thereabout), it's the only night I will have Aging On. So, every lifestage will indeed experience every season. Aging them up to their next lifestage is something else and will not affect this at all. It could be the other way around, having shorter lifestages to make sure my generations will move on a bit faster. With 56 simdays per year, each lifestage could easily be 1-2 days shorter, and I would still get plenty more gaming time with everyone. Time and age is a mystery in these games, I easily get confused :)