I have the same policy.

I have had an exception to the rule though so not every child can follow the policy.

I have been training a boy for the past 8-9 months in pull-ups as per my contract. We were making zero progress. I finally told mom I wanted to just try underwear. I said if too many accidents we would go back to pull-ups. The first week was an accident daily and from then on an accident a week. I didn't go back to pull-ups! He is now fully trained other than will not tell me he needs to go. I just send him at 9, 10:15, 12:30 and 3. We still have the odd accident but maybe one every few weeks.

I also don't have carpet so easier to clean. Maybe leave in undies and send to the bathroom more often.