Performing any work (software or hardware) on a personal computer is an amorphous event. You don’t know how long it’s going to take. You do know what you have to do. You don’t know if any other problems are going to arise in a system composed of dozens of parts from dozens of different manufacturers. You don’t know what’s going to go wrong in the dozens of programs composed of hundreds of thousands of lines of code.
It’s a miracle the thing boots up at all.
Trying to gauge how long it’s going to take is like trying to solve the n-body problem. You really can’t solve it analytically. Poincaré, in trying to solve it, merely laid the foundations for chaos theory when he talked about deterministic chaos. And that’s really what it is.
Solving any sort of computer issue is improvisation. You know when you’re at the beginning, you know when you’re in the middle, and you know when you’re at the end. You know some moves, you know some steps, but until you start dancing with the problem—you just don’t know what’s going to happen.