it depends what you're trying to do.
i played hockey for a long time, and the best shape i've ever been in was during the middle of a season
in my opinion, nothing comes close to competitive sports to get you in well rounded shape. i was at my fastest, very strong, and i could literally go all day. i was also 18 years old, and you're able to train much harder without breaking down when you are that age.
as an adult?
whatever you can manage. it's honestly impossible to be in top form if you work 40-50 hours a week. you don't have the time to rest, you can't practice the same amount of dedication with what you eat. you're invariably a weekend warrior.