Depends on what I’m cooking, but always for chicken breasts. Roasting at a high temperature works great (it’s not the only way), but can mean the overcooking time is pretty small. It’s an easy way to respect the bird and get the best results possible.
Thighs on the other hand, I just go by eye, you really have to try hard to overcook those.
Might be worth noting that using a thermometer well does require some amount of skill and experience, you need to insert it into the right location for the data to be repeatable. Easier to learn than cooking by eye, though.
The ten commandments are future imperatives, but English doesn’t have that mood and instead archaic language is used in place of it.
They are as strong a command as can be given, but a literal translation would just be “you will not”. That lacks the weight of the original form so translators try to make it read more seriously than the language allows with “thou shalt not”.