You can prune your catmint now or anytime for that mater! I struggle with Gaillardias but they would usually have died back by now (except this past fall)so I can't see why cutting them back now would be a problem. I don't cut back things that are marginally hardy for me like many Salvias and Lobelia tupa etc until spring when I see signs of life.

These are all herbaceous plants that normally lose their tops every year and grow new ones in the spring. Any that might have seeds useful to birds during the fall and winter could have spent tops left for that reason. Otherwise these could be left for any winter protection they might happen to confer, of if nothing else to show where the roots are located where stepping on them or burying them might be a possibility.

Perennials prone to being rotted out by fallen and matting tree leaves or having the new shoots destroyed by slugs might need to have spent stems removed in fall so that such debris can be more easily removed. A common example of this type is the chrysanthemum, its aromatic and grayish foliage indicating it wants an open and well-drained situation with no tree debris present.

Be sure not to walk on wet soil. You can prune now or later, but you want to avoid compacting the soil.