All I can say is that I've been doing it this way for three years and my system just works. Occasionally I'll hear a little something, usually really close to one of the preset notches. I widen that notch a touch and it goes away. You guys can say "it wouldn't work" all you want... it does work, and works VERY well. I've spent a lot of time tuning these presets.
I deal with six to eight handhelds hot on my stage at nearly all times plus a high gain lectern mic or two, high gain piano and bluegrass sections, high gain choir mics.... it's crazy on some of these stages. Earlier this month I took this, which was only part of the mics on my stage, and at times all open at once:
Add to that collection a few more of the sd condensers, another countryman isomax (both on piano) six wireless Sennheiser handhelds, and a da cappo headset, all roving around the stage and MOST in two or three of the four monitor mixes, all done with wedges. Six wedges on two mixes had to be loud enough for a 400 person choir. Choir mics WERE in some of the band wedges. No feedback for two weeks. My system works.