[mactec54]

In Mastercam, that Z.5 is my clearance plane.
I use it for several things.
A visual check for my guys to run an operation in single step mode and see that they set everything correctly. It's usually 1" above zero.
Clearance for getting around clamps when I have parts clamped to a plate.
And on some parts, where the depth is critical, we actually run the program to that point and stop it. Set the Operator Z zero there, and check it with a gage pin. We can then jog the tool up or down until it's perfect, see where we arand adjust the tool offset.
It already serves a purpose in my world.

I did change the post yesterday to format the line as G53 G90 G0 Z0. Because I am a fan of things being in a sensible order, even if it doesn't make a difference.

The end of my programs send the table to yet a different zero. One that we set to be easy to swap out whatever part we are running.

G01 X-.0216
G03 X.7126 Y.3309 I0. J1.9885
G03 X.7411 Y.3468 I-.0461 J.1161
G01 G40 X.7652 Y.3647
G00 Z1.
M83
M9
M5
G53 G90 G0 Z0.
G00 G129 X0. Y0.
M30
(PUT ANOTHER PART IN THE MACHINE RIGHT NOW, JERK)
%

I wired a buzzer in to the machine at the M83 solenoid.
I didn't like the way Haas changed there beep some years ago, so I figured out my own.
Works great.

Thats old school craziness using a Gauge pin or anything that is hard to set a Tool or to check a Tool set height, you damage the cutting edges of the cutter by using this technique

Machine some aluminum or hard plastic blocks and use that, to check large Tool offsets or plastic shim down to 007" works very well and is much more forgiving than any hard metal, just rubbing a Gauge Pin or a Gauge Block damages the Cutter the first touch, Plastic is the best Aluminum at a push

Your Clearance Plane is wherever you want to park the Z axis after an operation, you are making things more complicated than they have to be