yep

One thing to check If you think your scope is off, is the action screws. Most of your quality mounts these days don't move if installed correctly. But I shoot my rifles a lot even during deer season trying out different bullets, powder and headspace ECT I've noticed my action screws need to be torqued 2-3 times a year. Why I'm not sure. My better stocks don't seem to need it as much, but this synthetic on my weatherby does..
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Something isn't right. I have a 25 y/o Leopold vari x 3 on Leopold mounts that haven't been touched since I sighted it in 25 years ago. It's been dropped about 8 ft out of a tree and landed on the scope.

If you have to "re zero" your scope from year to year, you are experiencing optical failures. There is nothing preventing that same thing from occurring while you're out hunting- in fact, when a rifle is being used, it's more likely to experience a failure like this.

Hate to be that guy, but it's likely your scope. Vortex gives great deals out regularly, but honestly, their reliability is low for most models. Look into a Trijicon Huron or Burris Veracity. Also, before you add your loctite to the threads of your screws, make sure to degrease *every single* metallic surface of the rings, bases and receiver that will be touching each other, including the screws. Sometimes leftover oil from the manufacturer can cause screws to loosen.

Just to pile on AND as everyone has stated. Something is VERY seriously wrong with your scope and/or rings. With the exception of maybe a click or two with different bullets, I couldn't tell you the last time I was WAY off.

To eliminate the obvious:

1. Is the scope touching the barrel of the gun (bases too short)? This will cause erratic sighting in and VERY unpredictable shooting in different temperatures.
2. Are they the right size rings for the scope? 30mm vs. 1"
3. Did the person who originally installed the rings and scope use shims?
4. Is everything tightened correctly and to the correct specifications?
5. Are the screws or threads stripped?

If the answers are: No, Yes, No, Yes, and No - then throw the scope in the trash and get another scope.

I think he is referring to "bedding the mounts" with epoxy so the fit is perfect. When you do that, you wax the receiver so the epoxy sticks to the mounts only. You then remove the mounts, clean up the receiver then install the custom bedded mounts with screws and loctite.. This eliminates any non-contact surfaces between the mounts and the receiver.

Could be.