A timer left running while you made coffee isn't the same as one left running while you worked.
Start a timer, get pulled into a phone call, forget about it for twenty minutes. It happens to everyone. The question is what to do with those twenty minutes once you notice — bill them, delete them, or something in between. I don't think there's one right answer, but I do think pretending it doesn't happen is the wrong one.
If you undercharge because you're too honest about every distraction, you're quietly discounting your own work. If you overcharge because you never notice or never adjust, you're eroding the trust that got you the client in the first place. Neither is a great place to end up, and both are easy to fall into if the only tool you have is a manual timer with no memory of what actually happened while it was running.
The point of idle detection isn't to catch you doing something wrong. It's to give you the information to make the call yourself, instead of guessing after the fact or not noticing at all. Bizily's macOS app watches for a stretch of inactivity — no keyboard, no mouse — and after a few minutes, it flags the idle time and asks what you want to do with it: keep it as billable, discard it, or split the entry so only the active portion counts.
That's it. It doesn't make the decision for you, and it doesn't silently delete anything. It just makes sure the twenty minutes you spent on a phone call don't quietly become twenty minutes of billable client work by default, and that you're not the one who has to remember to catch it.
My own rule of thumb: if the distraction was about the work — a client called, I was thinking through a problem away from the keyboard — I usually keep it. If it was genuinely unrelated — coffee, a personal call, staring out the window — I cut it. Your mileage may vary, and that's fine. The point isn't to have the same rule I do. It's to actually have one, instead of finding out six months later that a third of your tracked hours across a project were idle time nobody ever looked at twice.
