This was quite a bit more convenient when we were getting our music on CDs, because many CD players included an A-B repeat function. This let you designate two

This was quite a bit more convenient when we were getting our music on CDs, because many CD players included an A-B repeat function. This let you designate two points in a track ("A" and "B") and it would endlessly repeat the segment between those points. I believe some MP3 players also had this. As far as I know none of the top streaming music services support it in their official interfaces. I believe it can be added via third party tools, but it would be nice if the services would build it in.