once on my 929, i was riding along and while going over a traincrossing, it was far bumpier than i expected and i got tank slapping as a result...it recovered quickly, but ever since that time, i've always had a GPR.
When i'm city riding it stays at a certain level - when i'm going for a highway jaunt, i turn it up a bit- you need to get used to having one cuz if you dont' turn it down once you get off the highway, good luck making that turn at the end!