It really depended on how hard you ran them. I knew some guys only doing the airheads ever 6000 miles. I don't remember what the book called for. The Oil head called for 6000 but if you ran it easy, 12,000 was good. But, even on the oil head, an hour max with a 20 min coffee break.
My KLR is 2 hours without a break. And I've been there over a dozen times between 3 KLR's. The last valve check I did on the main street bike was my DL1000 and that was over 6 hours and had to wait on shims. I have no idea on how much time it would take me to do the Bandit for the first time.