Really depends on the wire gauge and what I am using it for. Recently stocked up on the Amazon Sale with LV, so ive got enough to last me a good long while. I use 24G the most so Ill use that as my baseline. If I am just building for me, 30ft will last me about 4 months, when I add in building for friends and family, I end up going
through about 30ft every 2-3 months. If its high gauge wire for rolling claptons or anything like that, then I can make a 100ft spool disappear in a day. (I tend to build in bulk when it comes to fancy wire)