I have a lot of villagers who are 14 years old to day. Some of them find their way alone but the other not, even if they have some "inherit skills". Usually I bring them to do some thing according to their likes/dislikes preferably, but I think of letting them manage alone. Did you do that? And with what success?

I let them manage alone most of the time. If you're game is "completed".

Yes my game is "completed" Do they for a long time put making a success of anything?

Yeah. But it is still always a good idea to check every once in a while.