let's use steak as an example.
first decide what temperature you want in the middle of the food - if you want it more "done" than "rare", the internal temperature would need to be higher.
then, decide how quickly the surface temperature would be conducted into the food, it is a matter of physical concept, it depends on (1) thickness, (2) conductivity of heat of material
then, decide how you want the outside temperature. it would need to be higher if you want it browned. you want it to be higher if you want to release the aroma of herbs, but lower if you want the outside more tender.
fast cooking with high temperature leads to a crusted outside and a relatively rare inside
slow cooking with medium temperature leads to a tender outside and a relatively evenly cooked inside
very slow cooking leads to dehydration