the only patches I ever wore which where not standard scout issue where patches related to a spesific scouting event. these would go above the left side pocket, and might be related to a camp, competition, expedition or similar. these would be worn for a while, and then removed after a set period of time, usually about 3 months, sometimes longer depending on the situation, or replaced by a newer patch.
these never related to events, activities or groups outside of scouting, but could be related to one of the semi-autonomous groups within scouting (scout archery teams, bands, expedition teams ect)
only other bending of the rules was some of the guys like myself, who where linked to two seperate scout groups. for example I was a young leader at a local group, as well as being a member of a county level explorer unit, so wore both name-tapes.