I can't seem to develop a pattern. Usually wash my face in the AM with a treatment type cleanser (Lately by Dermalogica), but only manage to wipe my face down with a damp cloth at bedtime, just can't deal with washing my face at the sink.
If I wore makeup these days I guess I'd make a bigger effort, but ah, well.
If the treatment cleanser seems like overkill, I switch to one of my 'just a cleaner' products, simple face washes with no added active ingredients. The one I'm using mostly these days is by Paula's Choice, it's pretty simple.