Diarized
Overcommitment
Overcommitment is having agreed to more work than the available hours can hold. It is arithmetic rather than a character flaw, and it is invisible on a to-do list, which has no notion of how much time exists.
Also called: overbooking
Where it goes wrong
The usual advice is to prioritise better, which does not create hours. The only honest responses are to drop something, move a deadline or accept that something will be late. A scheduler is useful here mainly because it can show you which, before the day arrives.
Diarized schedules the work you already keep in a to-do app into the calendar you already use, and shows you why every block landed where it did.