Time, Speed, Distance
I'm 60, and 6' 1" with a 30" inseam, I like the European bars, have them on the Norton, the W-650 and the Hypermotard; the pegs are all stock. I have found, for me, that this gives me the riding position that puts my weight (230) in the right place for "neutral" handeling, although with the Ducati a bit further forward would be better.
I find that I can spend most of the day at 40-50 MPH backroading, or significantly less time as the speed increases. When my time is up, it's up, the symptoms are the same: stiff neck and shooting pains down the back, they clear quickly enough when I get off the bike, but return equally as quickly if I get back on too soon. If I need to get somewhere 50-50 MPH on a secondary road gives me about 150 miles before I need to take a long break or call it a day and head for the martini shack. Since my heart attack, which I had while aboard a Kawasaki KLR 650, I haven't tried any more 300+ mile days.
A few years ago I had a R1200GS, the best I could do with it was 300 miles/day before the pain started; that machine had a real dead air zone behind it's Areo-Flow, at any speed, I spent zillions on different bar/peg combinations, some felt better from a handeling point-of-view, all failed me after 300 miles, or so.
RS