We used craft sticks this year too. At 1/4", the bees were building on either side, but not the center. We pushed them up so they were showing between 1/8 and 1/16". That was better. After a couple of months we noticed that the comb was way off at the bottom and then we realized that the earth had shrunk so much because of the drought that the hives were out of level. We leveled them again and things have been better.
It's really important to get your hives level.
Also, we tried a few different types of frames - the slat ones, and the ones where you push the wedge over, then staple it in place and the ones with a plain old wedge. The bees don't seem to care. I like the plain wedge ones best [from Kelley]. Less fuss.