One additional rule of thumb> the engine should never slow on extended vertical flight .
this can be tough on setups which are underpowered but the prop load INCREASES as the model speed DECREASES and this all shows up as increased internal heat.
I am assuming full throttle during this example.
The engine sees this the same way as it would if held at full throttle on the ground and run wide open.
This is a maximum load situation.
Max load means max heating potential.
So use your ear for correct settings if you can.
Avoid adjustments which allow a cold engine to slow up after a moment at full throttle.