<p>When using a filament based printer, what operator behaviors increase the frequency at which a bed must be relevelled between prints?</p>

The only ones I have found are.
Manually putting pressure on the bed when removing prints.
Removing the bed covering, eg a glass plate
Damaging the bed in some way. For example my bed has high spots on it (always has). This means that if I remove the glass plate I use and put it back, it sits slightly different. If I orient the glass a different way from prior it always needs levelling.
Changing filament types.
Changing cover types eg magnetic and glass are different thicknesses.
Changing first layer needs. Sometimes I need the first layer squished a bit depending what I'm doing.
Lastly on my Ender 3 Pro if the z-axis switch isn't screwed in tight enough it can slip down a fraction.