Having now visited Roughting Linn in Northumberland at https://w3w.co/amending.unspoiled.national I feel that my previous suggestion wasn’t correct. A significant proportion of the marks have channels, and it’s clear the channel marks were made as part of the original mark. It seems unlikely that individual cup and ring marks were made over long periods, I.e. there was probably a single making event. My current thinking is that the cups and rings were made one at a time, and not very often, otherwise there would be many more of them (why are there so few)? I’m thinking that they may have been created by shamans on behalf of other individuals, and infrequently. If the cups represent individuals, the the rings might be conferring a level of spiritual protection, or healing, around the individual. The channels could represent birthing, so possibly represent a charm for fertility, or protecting pregnancy.