Usually I get 4-5* 18 y/o FTs. Training from 100% to 120% takes, I guess, 120-140 rest packs. I don't remember exactly, sorry.
With some effort and good resource management it is possible to have your whole team on 135-140% at the end of the season (no tanking, no buying tokens). It will take at least four seasons though, if you are building your team from scratch.
It wasn't our day.