Changing arm angles during a game?

We all know how pitcher Orlando Hernandez has made such a stable career for himself by mixing up arm angles and such but my question is: Is this effective?

I mean why dont pitcher today change arm angles more and mix it up to mess with the batters head. Instead of standardizing it with the one arm angle.

Ex 1st pitch fastball 3/4 high angle
2nd pitch curveball 3/4 angle outside
3rd pitch 3/4 low fastball or changeup etc.

I mean hitters can see when a pitcher is an over hand pitcher but drops his elbow or arm during a breaking ball, couldnt he manipulate this and use it to his advantage???

Id like some feed back because im a risk taker and willing to do anything to get the upper hand.

In order to not tip your pitches based on arm slot, you need to be able to throw all of your pitches from all of your arm slots. It’s probably easier to master your pitches from one arm slot than from multiple arm slots.