exsample, 3 unresolved stack actions. with interrupt set to 5 secs, will allot you 15 secs to decide the first action, then 10 secs to decide the 2nd action, then 5 secs to decide the last action.
note: its multiplicative, this does not make each stack action into 15 sec interrupt.
as they resolve "extraTime" gets recalculated.