flat of cue rotation?

Random thought: is it customary to hold the cue rotated the same always - put another way: do you have to keep the flat piece at the butt of the cue pointing in the same direction everytime, every type of shot?

I tend to always have the flat pointed upwards lately, but I used to rotate it down when attempting a power shot because I felt I could keep the cue on line better untill the final 'squeeze'.
Now I focus more on keeping everything more relaxed and let the cue do the work and follow through, instead of using more force, same effect but smoother.

So what do the pro's do: the flat always tot the same side? and doesn't the tip wear off more uneven this way?

On a snooker utube teaching channel the guy says about it is always best to use same tip part and is best for feel, also i think alot like to follow the Vs down the cue on their ash cue shafts as well for aiming, but maybe it is like alot of things is a mind thing more really and whatever feels best for a person.