Time is money. If it's a lettering job that's easy, we usually roll in the price of design.
But if it's a wrap, or partial wrap, you are darn tootin' the customer will pay.
Which, gives me a chance to bloviate about a past customer.
We had a fellow, a repeat customer, come in who wanted a re-design.
I sat down with him. After a while, it became apparent this was going to take some time (and fortunately it was a Friday afternoon and I didn't have anything scheduled.)
I told him after the first 20 minutes or so, we were going to charge him $xx per hours. He told me that his company (an tech design firm) doesn't do that. I told him, we aren't his company.
Three hours later, we have a design. He asks for it. I tell him to give me a deposit on the job, but at any rate he owes me for the design. He pays me.
Next Monday, he sends me a completely different design (not set up to go on a truck) and he wants it on the truck in a day.
I tell him no way.
He wants his money back (which was equal to our hourly rate.)
I tell him, sue me.
Never heard from him again.
Good riddance.