like mouse said, this isn't your responsibility. if your T really did have a problem with going over time with you, she would simply say "we can discuss this next session" or something.

as for healthy modeling, i'm not sure... some Ts prefer to run back to back for a while, then take a loooong lunch break (like my pdoc - he disappears for 2hrs), whereas some Ts prefer to have 10mins between each session (like my old T, who never scheduled a lunch break on the premise that at least one of his clients would cancel that day).