You're an idiot if you think that there isn't a best setup for any given situation. Being able to figure out what that setup is is another story though. Just because there are a lot of possible combinations that can be successful doesn't mean they are equal. There is a big difference between needing 8 hours and many wipes to complete an instance and being able to run it in under an hour with no wipes. Theres also a difference between a 52 minute run and a 51 minute run. Just because you can't tell the difference doesn't mean it isn't there.