Not exactly - especially with the ABC/ABN metallurgy in modern engines. The old cast iron pistons running in a steel sleeve or ringed engines you could (and should) run these pretty rich for the first few tanks.

An ABC or ABN engine has a brass cylinder which is fitted tighter at TDC than a ringed or lapped iron motor. If you run it too rich the cylinder won't heat up to get the running fit it needs. You'll prematurely wear the engine out.

Note - it is far more beneficial to run an engine in short 1-2 minute runs then let it cool completely between runs vs. hooking up a 20 oz tank and letting it run an hour.

Best bet is to follow the manufacturer's recommendations - especially in fuel and prop selection. Don't overload an new engine with a too large prop.

I broke in my TT 46 Pro by mounting it on a test stand, put a 10x5 prop on which had been balanced and ran a 2 oz tank of 10% nitro with 20% castor/synthetic oil content fuel (such as Sig Champion). I ran it with the muffler on and muffler pressure (it didn't want to needle without muffler pressure). I started it, peaked it out to get it to heat up then backed off about 1/4 turn of the needle. It was running in a fast 4 cycle and barely breaking into a 2 cycle setting.

My TT 46 Pro is one sweet running engine. I don't even use an electric starter anymore - just choke it twice, hook up the battery leads and spin the spinner clockwise with my fingers. Rotate the prop counter clockwise until it is resting against the compression stroke then smartly twist the spinner clockwise. The prop will act as a flywheel and the engine should fire when it hits the compression stroke but bounce back and start running forward.