I was yesterday working on a field of 20 ha an average slope of 0.017% and 0.04%. Very little dirt was moved to make it flat but I do not like it.
We would not generally go below 0.05% minimum slope in main slope direction. Prefer 0.066% minimum if not too much more earth shift. If earthworks are less than say 100m3/ha we will often increase minimum slope and smoothing and reduce maximum slope until earthworks get up to 100m3/ha or more.