I get what you’re asking and have noticed that even with the thermostat trying to avoid it, the stove temp goes down near the end of the load unless you turn it up. Isn’t that what the thermostat is supposed to do? Well, it’s not perfect. Works the other way too where it gets a little warm at the beginning of the load. The bulk of the burn is nicely regulated.When I set my Sirocco 20.2 thermostat to 3 o'clock it keeps the house a nice 72ish degrees until the load is about 3/4 burned. At the end of the load I have to start turning the thermostat up to maintain the same heat output. By the time it's burned down to a few coals and ready for a reload the thermostat has been set on high for a hour or two. Shouldn't the thermostat keep the heat output the same until all the fuel is gone? It's less of a problem when burning Spruce as the coaling stage is shorter than with Birch. With Birch the thermostat has to be turned up several times in order to keep the house warm while burning down the coals enough to do a full reload.
I use this behavior to my advantage by letting the house cool a bit to absorb the extra output from the next fresh load.