Never underestimate the power of snow to slow down the freezing process. Geese, wind, depth changes, and water color (dark water absorbs and retains heat better than clear) can all make a big difference as well. Wherever you go out, if the ice is 4″ in one place it does NOT mean it is safe to walk everywhere on that water. Macbride, for instance, is notorious for having a lot of booby-traps, especially under the power lines.
I have not had time this week to check ice around IC, but one shallow pond that was skimmed over last week has a good blanket of snow on it that would make me wary of just walking out on it. Another deeper pond was still open Tuesday morning, and I am betting that ice is in better shape. (I am going up to Minnesota this weekend, so SE Iowa ice conditions are of little immediate concern to me. )