The token ones are usually fast trainers. Since he cost 24T then he is at the higher end of the spectrum. I'm guessing in two full day of training he will be 5 stars. So far all the 24T youths I receive have been fast trainers.
Again, it is a matter of preference whether u sign him or not. You can go into a bidding war for youth players, so spending 24T at one go is a price for convenience. Of course if he was generated on the last day of the season I would opt not to sign him. Personally I've singed a couple of 4star players who are currently a regular in my team and one of them is still training his socks of rather slowly since I don't train him every hours but 3x a day.
I always avoid bidding for youth players and rely on my academy, tho I don't sign all of them.
If he was in a position that you really require then maybe it is a good idea to do so & sign him. Despite his 4 star I am pretty sure he will pick up a few MoMs along the way...