This is just my opinion. The worst heavy tracks are those where the rain has come down a day or two before the meeting. Why? I don't know. I just remember a lot of unfancied longshots win on those days. When there hasn't been a heavy track for quite a while, it can be treacherous. Even good wet trackers don't do so well quite often on those days. But in the middle of winter when there is a lot of slosh about and a lot of slosh form too, its like any other day.