I usually check them about once a month when busy, once every three months when not, or whenever my crap starts acting funny. No way I am gonna do it daily, but once a month for every filter is enough I think.
I mean, c'mon. You got one in your wand, one in your RX-20, 3-5 in your machine, two in your hydroforce, one in your chem draw, one in your stair tool. I'm not taking all those out once a day. You're lucky if I check my pre-filter once a day and the blower filter 3 times a week...