Glow plug temp corresponds to how much methanol is in the fuel. Less methanol =
Colder plug; more methanol hotter plug. The slight exception is when using high nitro and high oil content; in this case a hotter plug is better.

I run HOT plugs up to 25% nitro. 8-25% oil. No issues here in MN.

I even use 4-stroke plugs on problem engines with high nitro without issue. I usually only use a 4C plug to diagnose a problem and swap back to a normal hot plug when it's sorted out.