If I remember correctly the RAF limitations on WEP use was on a per flight basis, so if HiTech were very strict there would be no WEP "recharge" in British aircraft at all. Of course these WEP limitations were for the most part intended to maintain the service intervals of the engines to a sustainable level. There are examples/anecdotes of pilots running on WEP for far longer than they should have because they were in distress, and no one would blame them. After all the operational limits are only there in case there is another flight by that particular airplane. If subsequent flights do not appear likely, there are no limits.