Every time when i dont collect them for long periods of time (say 2-3 days), i come back to find all my dwellers being maxed out on the SPECIAL stat they were training on.
Now i open the game often, but every time i had to leave it for a few days i have noticed that this happens. Its possible that everyone was about to max out at the same time. But this world isnt perfect, and I cant be that lucky.
So, does the dweller continue training even if it was left unattended for extended periods? if thats the case, i can just dump a bunch of dwellers and leave them there over the 2-3 days (total time needed to max a SPECIAL), and come back just to switch them to a new room.