I like to say thay mine is an equal partnership- he finds the work, I do it!
Being so close to the "sharp end of the stick," I keep in mind that you can't always charge the customer for your "support" time. If I do several small jobs in a day, I may have to put in 11 hours in order to bill for 8. That's the nature of a small business.
It's also something to consider in setting your "hourly rate." The customer would rather pay $60 for an hour of you actually working, than $60 for an hour of work and an hour of going to the parts house, etc (at $30/hr.)
