Yup - this is how I work as well... a simple service is charged with 500 SEK/hour (about $50 USD) while an overhaul often leaves me with somewhere between 250-500 SEK/hour, most often around 250-400SEK...My shop quotes a price for an overhaul, and it doesn't matter if it's 30 hours or 40, it's the same price. However our servicing is hourly. Sometimes overhauls come out to half our hourly rate
I still prefer overhauls since I feel that I have achieved something great.
I guess this is not the best way to make money?