ok when should i rest them

depends on your starters. backups can just gain energy back over time.

when training normal, you gain 1% energy each week. sometimes it's 0, sometimes is 2, by average it is 1 per week.

so if you cannot get your starter up above 90% before next season, 4 training updates, then rest them.

resting a player give you 10-12 per week energy increase.

you are gonna lose out either way. which is why heavy training is never recommended.

lots of you players have energy 85-90. so maybe set you rest level at 85, and training to normal. most player should be back in the 90s by next season.

or if you wanna just get them good asap, leave rest at 90 this week. most will only lose a weeks of training either way. and then lower it enough so the new low energy backup QB can still train while gaining energy each week.