Earlier this year I was making unglazed ^6 porcelain beads and fired them all together in an unglazed porcelain bowl. I never encountered any problems with fusing together. Once or twice I had to tap them a little bit with my finger to loosen them up, but they always came out fine. I also just fired some flat ^6 stoneware discs for another potter at my studio (flat circular slabs, fired in a stack of 4 or 5 deep) and they came out fine as well. I had to pull some of them apart, but it was easily done with my fingers, I didn't need to use a mallet or chisel or anything like that.
If your work isn't super paper-thin delicate you'll probably be fine... but of course it's always a good idea to test before firing a whole kiln that way.
- clayshapes likes this