One who discovers that he is impure after entering the Beit HaMikdash needs to depart as quickly and/or directly as possible. But what if he used the shortest route, but took a long time to walk it (or a long route quickly)? Also, one who enters a home that is impure because of tzara'at, that same person stays pure - if he walks in differently from normal. Plus, the kohen's check of the house for tzara'at. Also, the positive mitzvah that is included in the sum total for which one is not liable.