"I run MAC filtering"
"I haven't already added and recorded in the spreadsheet"
Why do you add this overhead to your management? What does it buy you? You clearly understand that without encryption traffic is in the clear - I could not tell if your running encryption or not.
I fail to see the point of mac filtering if your using wpa/wpa2 and PSK to limit access and prevent sniffing. Mac filtering could be useful if its a known psk to users, but for example you want to only allow their laptops and not their phones to access network. This is a control method, which is what mac filtering is.
Say very small office or even home, and I want to allow laptops on the network but not all the ipads/iphones/smartphones/kindles/tablets/etc on the wireless network eating up limited shared bandwidth. So I use mac filtering to only allow the devices I want because the same users that I give the secure psk too also have these devices, etc. Now hopefully these devices are harder to change the mac on than normal pc/laptop - and again its a control method, not a security method. We all know mac filtering is quite easy to circumvent. But normal users are quite dumb - so many of them will not understand why their iphone can not get on the wireless network but their work laptop can, etc
And even if they knew it was mac filtering, they hopefully do not have the skill set to change the mac on their iphone - if they did they would prob be working in your IT dept
Mac filtering can be used to control which devices can access network, but it is not a valid security option. So when you have a userbase than knows what your psk is, or has valid credentials to auth to wireless via enterprise setup and you want to control what "devices" access the wireless then sure mac filtering is primitive version of that. In enterprise you would prob use 802.1x with EAP-TLS so that devices have a cert to be able to get on network vs just mac address.