Last night I loaded the stove with three really massive slabs and a little bit of filler at just before 10:30 last night. Stove top is currently sitting at 254 degrees with the sides sitting at 320-340 degrees. This is the longest burn I have had with the 30. A few things with the big slabs: They took longer to get going Stove top temps were 600-650 as oppose to 700-750 Stove top temps stayed north of 550 for over 6 hours (I got to bed at 4:30) Coaling and split break down took forever. 6 hours latter and the big slabs were maintaining their shape.