The whole soil puryfying phase could be perfectly skipped then. It's just a part of the submod. If you play with more soils, you have to split soils' components to get clay, sand tan and silt and maybe nuggets. If not, you directly get clay, sand tan and... not silt, well, it's just a useless byproduct by now. You can also dump sand bags and silt buckets with a skill-less (i.e. instant) reaction.
The steps are just 4-5, two of which are automatic, and the failing chances are there because you really have nothing to lose and to encourage an expert potter. Clay is unlimited.
Really, to me it seems simple:
Collect clay. Purify clay Redacted. Couldn't afford FPS-eating geological variety. Shape clay to item. Let clay item dry. Fire item.
Dirt works sometimes, and sometimes doesn't. I think it depends wheteter its name appears betwen parenthesis. Clays have this problem as well.
Anyway, how much does the "more soil" option impact FPS?