You just get to know your setup over time. Iirc i heard bobby from brewhardware say that a little warmer is better. And i agree, you can always cool easily, but heating especially once grain is in can be tricky. A lot depends on where and how you store your grain. The grain temp, outdoor temp, etc...play a role. You were perfect in the above example and just had to stir down till you got to your desired temp. I use 170 for my 10g batches because i use two bags and it takes some time to get both bags filled with grain and doughed in.
If you think about the brew day, the grain, temps, time it takes to dough in and stir etc...i bet you can already kind of plan for what if anything to do next. If to hot just stir down to temp as mentioned. I plan for a solid 5 min stir. I like stirring it really well, i mean really well. I hold the cheap plastic mash paddle anchored against my chest with one hand and whip the bottom violently with the other. While kind of holding the bag a little shut too so i dont get splashed. If the burner stays warm i think that would be at least somewhat desirable to help hold temps as long as its not staying overly hot. I don't know why I keep insulating the kettle because I'm about certain that Mash temperature really doesn't matter or at least would be able to be perceived in a blind taste test. A hydrometer might measure a few points different.
A final thought is to add ice maybe or boiling water as a way to quickly adjust temp but will obviously mess with water volumes.
