Fluctuations are normal, it depends on usage and load on the battery and battery types. E.g. Alkaline batteries show more voltage drop vs Lithium batteries. Also as the battery ages it fluctuates more, so when using an Alkaline batteries you’ll see more fluctuation at 50% battery life when the deadbolt motor operates than with a Lithium battery (NiMH and NiCd batteries are even worse and a high fluctuation can cause the lock to stop operating due to the voltage falling below the minimum operating threshold). If you’re seeing high battery level fluctuations when operating the lock (10% or more) it’s best to change battery brands or replace the battery at 50% for deadbolt locks and 30% for electronic locks.
See these topics for how batteries in locks work.
Schlage Door Lock Battery Died Suddenly
At what percentage to change batteries in Schlage lever lock?
Yale Deadbolt BL1 Battery Percentage at 1% at Randon
Yale Connexis L1 Battery change
As for refreshes, it depends on the DTH. The stock DTH relies on system polling, but that’s been broken for a long time. Sometimes it polls for some devices/users and then it does. If you’re using the Enhanced Z-Wave Lock DTH, that requests a battery update about once a day if the lock doesn’t report it. Some locks report the voltage when it crosses a threshold so it’s really a combination of the lock, platform and DTH.