Rick, I found the same thing with "substantial" wads blowing patterns.
When I first got my 16ga, I used the conventional 1/8" hard o/p card and 1/2" fiber cushion and had fairly frequent blown patterns. When I started splitting the fiber wads in half, my patterns improved markedly. Since lubing wads at the muzzle was inconvenient, I tried Crisco-soaked 1/4" fiber cushion wads and got similar results to the hand-lubed ones.
After reading discussions about the 1/8" hard-card possibly affecting patterns, I tried using multiple overshot cards instead. It APPEARS to have improved the consistency of the patterns, but I have not shot and counted enough patterns to prove it rigorously.
I was out patterning recently, trying to test powder-to-shot ratios, home-made shot protectors and such, but all I really managed to prove was that a Crisco-soaked 1/4" cushion wad becomes a pattern disrupter when it's below freezing. Plain o/s cards without the lubed cushion worked, but loading got difficult quickly in my rough bores without some sort of lubrication and one cant do a V.M.Starr and lube the shot directly when you're using a shot protector. BUT oiled ~1/4" cushions cut from boot-liner felt turned out to work fine, even when somewhat uneven (I'd repunched them from 12ga, and they hadn't always been straight and centred when cut).
I had been soaking the fibre wads in melted Crisco and squeezing the excess out, and they work fine down at least into positive-single-digit temperatures (high 30s F, for those south of the border), but they are apparently too hard and dense at ~-5C (mid-20s F). I hadn't realized for a while that they might be the problem with the consistently blown patterns because I could see a nice 10-15yd trail of fiber-wad shreds in the snow. I guess it should have been more like 5yds. Then again, I found one of the oiled-felt wads sandwiched between a card and the shredded remains of a paper shot-protector right in front of the 25yd target and the pattern looked OK at first glance. I would guess the difference is in the lower density and/or stiffness of the much-more-compressible and much-less-saturated oiled (with excess squeezed out) felt wads. I'll have to try oiling and greasing the edges of the regular 1/4" fibre wads and see if either (or both) work.
I've gotta get out and experiment some more, but I always seem to be short on time and ambition to mark and count patterns afterward.
Time to go make supper - hope this helps.
Joel