^ what he said - you're looking at a max of 10 screw's in most cases.
6-8 for the board , 2-4 for GPU & other expansion card.
Most cases have thumbscrews on the side panels , & screwless fixings on the drive bays.
These screws are a max of 6mm long which means 4-6 turns is all you need to do , a mid sized Phillips head (pozi-drive) screwdriver is all you need - hardly easier or quicker using a power tool!