Yeh, just thinkin of my backyard mechanic experiences...
Tighten a bolt, smoke a cig and grab a beer
Tighten 2 more bolts, wipe sweat off forehead and grab a beer
Tighten 3 more bolts, smoke a cig, wipe sweat off forhead, grab a beer as I am going to take a leak
Check if it's right, grab a beer
Read the directions, toss my 4 empty beer cans in trash
Re-read the directions, grab another beer
It goes on and on... no wonder it takes the backyard mechanic 250 hours!