2 things to keep in mind.
1. On a hot day it will run hotter. On a cold day, it will run cooler. You are not going to get an engine to run at 260* safely when its 40* outside. If you do, more then likly you are too lean.

2. All engines are different. Even the same engine, from the same company may be different. So if one runs great at 220*, anothe may run great at 250*. This is normally not the case when using the same brand and type but different brands will do this. Alphas and Reedy motor like to run hot (250*+) while Sirio and OS tend to run a little cooler (200*-250*).

Its a crap shoot to say all engines run at a said temp. Just find where it likes to run at and keep an ear out. Use your temp gun to check if you are unsure about which way to tune. Its a tool. Just like a screwdriver or wrench.