So, fire it up and burn half a gallon while adjusting the tune to keep it running without stopping the engine... You have done this personally on many engines I take it? Many engines you keep and know how long they last and how they were maintained?
I'm not doubting really, just curious as that sounds a heck of a lot less annoying that heat/start/stop/cool and repeat 5+ times, which I have been doing for the past 10+ engines I've owned. Every one of them ending with blistered/bleeding fingers by the time I was done for the day... I love pullstarts... except for break-in.
It has been a very long time since I've had an engine "wear out". If I had to guess, I'd say the 3 I currently have are all about 3-4 gallons into their lives (2 LRP28S3 1 TRX2.5R), except for the 3.3 I put in my revo for the winter. It's probably at 1-1.5 gallons.
The last engine I had long enough to lose it's pinch was an OS21RG, it started flaming out around gallon 10/11. I had it pinched and ran about another 5 through it, then started trying out other engines in the power hunt.