I always have my phone in my pocket. My billfold is stored in my car, and I do occasionally forget to put it in my pocket when going in to a store. Plus my billfold is thicker than my phone so it's less fun to store in a pocket.

I think this is very region specific. I'm in the UK and hardly ever take my wallet with me unless I'm going somewhere that I know to be cash only and might need to find a cash machine. Only other time I do take my wallet is when I'm in Germany where most places seem to dislike cards.