You're doing a job. It'll only take five minutes, all i need is that tool, hmm, where is it, i've only just seen it, it was in my toolbox right here for goodness sake!
...and by the time you've emptied out your toolbox to find the right screwdriver, it's taken four times longer than the actual job.
Sound familiar? Happens to me all the time.
A few years ago I was looking at Adam Savage's website, and was intrigued by his concept of "first order retrieveability": you can get to any object without having to move anything else. Here's a picture of one of his fantastically ridiculous toolboxes. Notice how almost all the tools are standing vertically so you can find them and take them out instantly.