I'm all about experiencing & interacting with the game world as the PC, so I consciously try to reduce my "meta" thinking about the game.
I wasn't always that way. I consider myself a reformed munchkin.
Now, all of that doesn't mean I'm not aware of system mastery. Its just that I bend the knee of my system mastery to the rule of making the PC the best version of him/her/itself as possible. And "best" doesn't mean combat optimized. It means that the mechanical version of the PC is as close as possible to the concept of the PC floating in my mind, which may or may not be sub-optimal or super tweaked.
I wasn't always that way. I consider myself a reformed munchkin.

Now, all of that doesn't mean I'm not aware of system mastery. Its just that I bend the knee of my system mastery to the rule of making the PC the best version of him/her/itself as possible. And "best" doesn't mean combat optimized. It means that the mechanical version of the PC is as close as possible to the concept of the PC floating in my mind, which may or may not be sub-optimal or super tweaked.