1e15 would allow an instantaneous step to 51%. I think I’m reading this as how much a single step can do, so that seems plenty generous (and not contentious). Even 1e14 would allow about 4% per vote – that seems about right to me, which probably means it would deserve discussion before getting set that small.
I’m ok with it being 1e16. I think it already serves an important purpose of being off by likely 3 or 6 orders of magnitude, and there will be review on proposals (else we have all sorts of issues).