Almost daily. I initially used twice a day but found that I was over-cleansing my skin. I now use a scrub in the shower in the AM (applied by hand only) and the Clarisonic in the PM. I've only skipped maybe a handful of days, usually when I don't on any makeup at all that day, or if I got too tired and fell asleep without cleaning my face (which doesn't happen often).
I've reduced my frequency of breakouts from once every few weeks to once every few months. I will never go back to just cleaning with a cloth (in fact, I only use a cloth to dry my face. I rinse by splashing water onto my face).