you can not isolate from all RF period lower Frequencies are easier. The sun bombards us with RF, every cell phone every wireless device is bathing you in High frequencies. shorter the wave length the smaller the holes in the cage need to be. I’ve been in shielded rooms on the Navy base that use 12" of various types of shielding the doors are 12" thick and the door seals have multiple copper wipers all around and they still let in some frequencies. so don’t worry too much focus on the ones that are audible.
oh Terry9 once you bend any metal you get micro fractures so when you anneal the metal, heating and cooling under control you remove the micro fractures. This is a point for wires to consider don’t bend them to much and too often.