There are as many schools of though as there are engines, and everyone has the right to their own opinion. Some will say you need to follow the manufacturer's directions to the letter, others will have their "Never fail" break-in proceedure that may require mixing your own fuel concoctions.

Personally, I run a tankful of fuel throught the engine at about half throttle with the engine running rich.

Then I go flying.

I'll leave it running a few clicks rich for the first three or four flights - maybe even leaning it out a little each time.

But that's about all of the break-in I ever do, and I've got many engines that are many years old and still running great.