??? what sticky mat?? If you use a sticky mat you just might rip the outer skin off!that is a good idea on the sticky mat! that will hold the foam still while I cut.
It depends on the actual part..but I almost always tend to hold the blade still only drawing it an inch or so as I TURN the foam-core or any curved paper cut...and real slow! I rarely hold the card still and try to draw the knife down the whole cut...