This is all obvious in retrospect; it is simple arithmetic, but that didn't stop me from missing it and its implications.
The traditional wisdom is that if I can handle a task in under 3 minutes, I should do it immediately rather than putting it onto a to-do list. This on the face of it sounds sensible but turns out to be problematic. Even with perfect estimation, the worst case here would be that every task took 3 minutes and nothing went onto the to-do list, this would take 300 minutes — 5 full hours.
That is not sustainable. It doesn't allow prioritization. It doesn't let me even skim every email for doing triage.
It simply can't work.
What I have been doing was setting that threshold at 15 minutes rather than 3 minutes and occasionally misestimated a task that took 45 minutes as in the less than 15-minute category.
With that misestimation and that strategy, the meantime was just over 4 minutes. 400 minutes for pass through my new email — almost 7 hours. The problem was not that I was leaving messages in my inbox / pushing them into the future. The problem was that I was all too often starting tasks without prioritization.
What I need is a triage system. A triage that system lets me drop that 3 minutes limit to 30 seconds.
When it is not possible to do everything, not everything will get done.
You can choose which of those things won't get done.