Each day takes about 1 hour, some a little, some a little more. I do abs 4/5 of those days also though.
I found the same with bench pressing, but the endurance comes, over a few weeks.
Started off like:
Incline: 15, 15, 12.5
Flat: 17.5, 15, 12.5
Decline: 15, 15, 12.5
So usually fell...