I have my 6 hives set up on 4 concrete blocks plus a pallet, SBB, two deeps, and then supers. Right now some hives have 5 shallow supers (a few are mediums) on top, and I'm wondering how high should I go. I only add one at a time when I see the tops being really worked, and have extracted some early, but really have about 8 weeks before I really extract in September. Anyone experience trouble with hives being too high? Any chance they will fall?