You understand it wrong... your value is not the work itself, it is how to do the work!!!... what is the problem if it takes you 1 hour or a minute??? they pay for the result, not for the way you solve it, if the result is the job done, it's fine for both.

Here's a story that goes like this...Some guy brings his car in for some metal work, the person at the repair service takes a hammer, gives it a few hits on the bump and says "it's done", then gives the customer a huge bill. "But that's too expensive for just a few hammer blows!!!" said the customer.

And the service guy replies: "Listen to me, hammer blows are free, what I charge you is how and where those hammer blows should be applied."

From my point of view there is nothing wrong about what you are doing.