Small change, HUGE improvement.
Once a dweller reaches maximum SPECIAL stat for that particular training-room, he will automaticly leave and go to coffee break.
Will still require clicking the levels but no more having to manage whos maxed and who aint. With 200 ppl that takes a while.
Somewhat related: "Auto-fill rooms" -option
Option to toggle auto-filling rooms. If a room has an empty slot and a dweller walks by, he/she moves in. ALSO works for training, reducing tedious micro-management. Some may want to min-max rooms themselfs so it may be better to be an option that can be turned on or off.