Optimising consistent star size through EAF?

Any good tips on how to more easily ensure a consistent focus across imaging sessions? I have my eaf set to recalibrate hourly. There are times my star size has drifted from roughly 4-8px. Obviously not ideal.

I use a dew heater and have it set to 70%, on an askar 103 and zwo 2600mc combination. It's winter down here, with temps to ~35-40F overnight. Bortle 4. Small stream at the foot of the property.

Cheers for any help🙃