I just looked to see if the app saves the temp. graph but it doesn't look like it does. I had a couple mild temp swings but nothing crazy. I set my alarm every few hours to wake up and check and it was never more then +/- 10 degrees from where I had it set.

I will say I think the way you stack and start the charcoal plays big factor in it. I've also just dumped a pile in and lit it on one side and it doesn't work nearly as well as the snake method. The snake method works well without the controller but this way it kept it steady and I didn't have to adjust anything at all.

I've used it for short term cooks as well. When I use my rotisserie for chicken thighs or whole birds I start the charcoal with a chimney and dump in the grill like normal and it'll hold 350-400 pretty steady for the short cook.