pH targets aren't the same from cow to cow, let alone cow to goat. There are some basic rules you need to stick to though. For example you need a demonstrated production of acid before renneting, I normally use a minimum of 0.1 drop, but 0.15 is best.
For some cheeses you need to operate in a pH window, for example if you hoop swiss at a pH below 6.4, regardless of your start pH or milk type you are asking for problems in eye development. If you make a camembert with mesophilics and the pH doesn't drop below 5.2 overnight, you'll have problems. Same cheese, if the pH drops below 4.7 overnight, you'll have problems. Within the bounds of the cheese type there is lots of room to play though.