Great example was Top 40s WLOF/950 and WHOO/990 Orlando in the late 60's early 70's. WHOO's quality was better, but WLOF sped up the music, making them have more "energy", and resulting in more listeners.In the 70's when just a few station discovered the process, it made the same music on a competitor sound draggy. There was a definite perceived benefit that one could measure when doing research.
Also, some Talk stations speed up some programs they get off network so they can cram in more news and commercials, but they do it digitally so the pitch stays the same. WSB/Atlanta was notorious for speeding up Rush Limbaugh; his program would start a minute or two later - delayed - and end each hour on time. It made Rush sound hurried (and his "dramatic pauses" were lost.