I have my life stages off the default, two for babies, nine for child, 10 for teens, 50 for adults, 25 for elders. But, I am doing personal dynasties, so I wanted such long days.
I went with that to some extent but also used how I personally feel about seasons. Winter is default, seven. Summer is I think 15 but Spring and Fall so far are set for 25. If it doesn't stop raining so much (five days straight in Fall?) I may change it, I don't want that much realism.
My sims so far haven't reached Winter or Spring season. Just Summer and Fall, not looking forward to Winter. I wonder if they have black ice in winter? Again, realism too far if they do.
Anyhow, I would suggest that you jut play around and find what works best for you. Lenghten seasons you like and shorten the ones you don't; or have fun and flip a coin or put numbers in a cup and chose one.