Be flexible in cancelling meetings. Be inflexible in adding them at the last minute.
Canceling meetings and adding meetings are not equal.
Canceling a meeting is often non-disruptive. When it’s cancelled, we can always choose to do something else, such as continuing to do the work at hand, or even just read or relax a bit.
Adding a meeting at the last minute, which often involves grabbing people to the meeting they’re not prepared to have, is almost always disruptive (unless, of course, the meeting added happens to fill up the slot of another cancelled meeting, which is rare). When dragged, we have to stop whatever work at hand or planned.
Disruption to work decreases effectiveness and efficiency. Canceling meetings doesn’t disrupt.
That’s why canceling meetings is more equal than adding them (especially at the last minute).
Respecting other people’s time and work starts with not scheduling too many meetings in the first place. In times of change, be open to cancel, and be very cautionary to add.