The plan that depends on every minute behaving perfectly has left no room for being human.

A schedule with no gaps is a schedule that assumes nothing will go wrong, which nothing ever manages. Traffic, a phone call, a shoelace, a body with its own needs: none of these are unusual events, and a plan that cannot absorb any of them is not tight, it is fragile. The stress that follows is usually blamed on the person rather than on the arithmetic that was never going to work.

Build the gaps in first rather than fitting them in afterwards. Put ten minutes between things and treat that as part of the appointment. If the day then holds fewer items, it will also hold fewer apologies.