Honestly, what your GM should have done, Jareth, was enforce distance penalties on perception checks to ID targets at long ranges, and also make sure they were doing those perception checks with no electronic enhancers not paid for with Essence, and applying the -2 to cast spells at targets you are using optical aids to target.
That, and all the other little ways to discourage that kind of thing already mentioned, that don't need houseruling to implement.
Lol. Yeah, he did that as well. He also had a chart for perception modifiers at specific ranges. He did well research on how far things could be heard, device levels, etc.
Due pool penalties (and TN penalties way back) could get a bit up there., Lol