Wouldn’t you? If I switch context and interrupt my flow to answer a question I’m losing at least 20 mins to regaining focus, why shouldn’t that be reflected in billing?

Knowledge work is knowledge work, no point belittling colleagues in a different profession.

Thats how MSPs operate too. At least the good ones. Billing increments are sometimes as low as 6 minutes, or as high as 30. 15 minutes is average in my experience.