I age my sims manually, but according to life stages I think I got from the game or EA back at release. I think most birthdays are fine, the only one I find unlogical is the change from teen to young adult as late as aged 29. Especially because University can not start until YA stage, it feels like they get too old before they are ready to build their new family. I think teenagers should turn young adult around 23+/-.
I let my adults become elders at age og 71, and then they will normally die at age 85-90 which I find quite okay.
PS: I'm glad we don't have any more life stages, because I find it rather tredious to bake all those cakes. Most of my sims don't even get to eat that cake, LOL. Wish there was another optional quick way to age up without a cake/party.