Vague hours are how a good client starts to feel cheated.
One number, no story
"Consulting, 12 hours, $1,800." They squint at it. You get defensive. The next block never gets bought.
An invoice with a round number and no detail makes an honest freelancer look like a guess. The client wonders where the hours went, and nobody wants to be the one to ask.
What Yoursellf does
You work on a timer that counts down the hours they bought. What they paid for and what they got are the same number, and both of you can see it. Every hour, and what it went on.