You could train stamina in short weeks, but when your trainee is young, it's hard to waste even a single week of training.
Better to use short weeks for 1v1/JS/RB training.
Then, if your trainees need stamina, or free throw training, train those when they are done with their other skills. ST and FT training aren't affected by age, nor by trainer level. So, bunch all that training together, use a cheap, low level trainer.