>jack up the front of my car enough for the front tires to be off the ground
>oil leaks out of the back of the transmission because of the angle, enough to where I have to add some.
>use my 2nd set of wheels and tires for test fitting things
>find that there is a nail in one of the tires, causing a slow leak.
I've done 3 hours of work so far today, and uncovered another 1.5 hours worth of stuff I have to repair. That ratio is average.