Just had a toilet replaced in our downstairs bathroom (don't worry, this post won't be creepy). It took the plumber one hour, from start to finish.
As you'd imagine, he didn't even break the seal on the toilet installation manual that he left behind for us. He does so many of these, I'm sure he could install a toilet with his eyes closed (not that I am recommending this).
For me, however, a toilet installation would take all weekend. Not only that, I'm certain the end result would not be nearly as good as what I have now.
If you ask me, that's the perfect client / service provider arrangement. The service provider can do the work reliably and easily; the client considers it high value because it would take him approximately forever and the final outcome would be much worse.
When you're putting together your list of services, look for that same intersection. Your clients will appreciate what you do and you'll get the job done without breaking a sweat.