How many windows do you have open with things half done?
How many emails partially written?
How many IMs to read? To respond to?
How many browser tabs with articles to read?
How many IDE windows with various code changes?
How many tests running in various terminals?
And now you have to reboot.
How many different tasks do you have to finish or at least get to a stopping spot before you could reboot?
Your primary workstation shows you how much of a multitasker you think you are. You're not really multitasking, though. You're simply not finishing things - maybe a lot of things.
I'm not particularly paper dependent - there are zero pieces of paper on my desk as I write this - so I use the reboot heuristic to remind myself to finish things. Ready?
If I have to touch more than three things before I would be willing to reboot, then I can't start something new until I've finished at least one.
The reboot heuristic is a reminder to myself that I need to finish things, not just start them. If I write an email and get partway through before I remember that test I wanted to start, that's okay. Repeat several times, though, and I'm spending more time switching between tasks than actually doing tasks. So three is my limit: when I'm doing more than three things, it's time to finish something.
Starting things is great. Finishing things is better. Multitasking is part of working these days, but not letting it get out of control - that's a heuristic I need.