This is the truth. Measuring work in hours only makes sense for work that you can only do when 100% applying yourself to the task (like brick laying or stacking shelves). Most of my high value output happens when I'm in the shower, riding my bike or going for a walk.

If that's your "consideration" then charge for it.

It's what other time based professionals such as lawyers do.

e.g. https://sherborneslaw.co.uk/pricing/