I did the wiping for a long time (at least a year or so after training at exactly age 3) and then he gradually took it over and I would do a 'check wipe' to make sure everything was clean. I don't think little kids do the best job really - maybe some adults as well - but that is the good thing about baths.
'Check wipes' will likely not be popular 5-6 times a day, though....