No drops are not necessary at all. The way you have the probe your are likely to get a natural drop anyway. Typically regular rooms get cooler over night and the ambient air temp is not effecting the probe so it continues to apply the same power even thought the ambient temps drop some.

In great room shifts it is often necessary to alter the set up or configuration of the herpstat. If you feel you need that ask and I can go into greater tuning. I don't keep a stable room temp so I am quite familar with the pit falls associated with that.