I do the same. Usually two tanks on the ground, then just fly a little rich for several tanks. On some of my engines, particularly the LA series engines, they take at least two tanks before they will idle. They will die below half throttle for a couple of tanks, and they really sound terrible, but after a couple of tanks, they settle right in and idle beautifully.

My FX engines, on the other hand, would idle on the first tank. I run two tanks through them on the ground anyway, before flying.

The Evolution .45 on my trainer took about three tanks before I got a reliable idle from it.

My other engines are Super Tigres, and they seem to require 3-4 tanks on the ground before they start to run reliably. I probably still haven't completely broken those in yet.

And I agree that an engine stand is not worth the effort, especially on these smaller engines. I have used a piece of flex tubing to keep the exhaust pointed down at the ground to save on cleanup.