The temperature gun or what ever is just an aid. Yes you need to be aware of all the other things I agree but running to hot is bad and it will sure tell you this. I fell anything under 270 or 280 is OK. As stated above good airflow is important as well. There are many variables but knowing your temperatures is a good one as to hot and you will destroy an engine. The other things you said are important as well and I do not tune by temperature alone. Bottom line what ever works for you and you do not fry an engine.