Wifey B: 5 minutes, 10 minutes, 20 minutes, 30 minutes every 3 hours, 4 hours, 6 hours, 10 hours. Pick one from column A and one from column B.
So, depending on engine what is best normal run. With ours it's 70-80% load, not throttle, but then fine to run at lesser speeds. Other engines made for lesss or more % of load. However, the one consistency I see is to at least occasionally open up to 70-80% of load and for just a brief time to WOT as WOT is your best means of checking your engine, prop, and more and seeing if you're getting the RPM you should. I sort of think of opening up once every time used but don't run WOT ever over 5 minutes or so as much as I like speed.
Moderation, but moderation doesn't mean to never open it up.