I, kinda, get trimming down center knobs for faster rolling. I'd be really curious to hear what the motivation is for only trimming them on 1 side. I wonder if it has to do with some handling bias, injury or something like that. I've been intrigued for years about the idea of changing setup to make up for bias towards a person's dominant side. Stuff as simple as setting up the bars a little crooked COULD make you faster I believe.