I heard David Allen (GTD) talking about our tolerance level for e-mail in our inbox. He thinks that we each have a level that we hover around. So, even if we reach e-mail zero we will quickly revert to our tolerance level.
I recognise this tendency. While I like to reach e-mail zero, I tend to tolerate about 15 e-mails in my inbox. (By the way, for me, inbox includes subsidiary folders.) When I get above this level, I begin to feel discombobulated. Although it might not seem like a big number, it’s enough to distract me, because I’m aware that I can’t mentally track what’s there.
Just to be clear… I don’t sit at my desk and monitor e-mail all day. I deal with it in batches at set times. My tolerance level relates to the residue when I stop processing. My preferred approach is to convert e-mails to tasks, which means that I’m confident that it has been secured. Then, I don’t need to retain anything in my head.
I also have a tolerance level of overdue tasks in my to do list. Maybe I’m a bit anal. (I should delete the word ‘maybe’ from that sentence!)