I don't keep much on the kneeboard, even for a long IFR trip. All I want is my flight plan, my clearance, and some note paper. I put the approach plate there for the approach, in some aircraft, but that's about all. Company paperwork and everything else goes somewhere else. I have seen kneeboards interfere with the controls temporarily, but it's quickly sorted out, by yelling "Get your damned kneeboard out of the way!!!". IMO, using large kneeboards and keeping the kitchen sink on them is a mistake, and causes trouble in the long run. I don't recall flying with any experienced IFR pilots who used large kneeboards, and many don't use one at all.