I think part of the confusion is we don’t normally have units for rates of change.

So let’s create one: the “walk” is the speed a person can walk — 3mph.

Then I can say the store is “3 walk-hours away”, even if I normally drive the 9 miles with my car.

3 walk-hours = 3 hours @ 1 walk = 18 minutes @ 10 walk (or 30mph)

Batteries are rated in “watt-hours” for the same reason:

3wH = 3 hours @ 1 watt = 18 minutes @ 10 watt