It is rather like mooring problems though - there are some hotspots, popular with pedestrians and cyclists, where there is an issue, but for much of the system there isn't a problem
I'm also going to be site specific and say that I am much more comfortable taking Magpie the Elder on the K and A towpath, which is part of the national cycle network, than I am on the Peak Forest, which isn't
I will add one further about both issues - why do people pretend that breaking the rules is okay? "Overstaying" may or may not be causing a problem at any given location, but if a sign asks you to move on after 24 hour, 5 days or two weeks why is there this collective "we don't have to and we're not going to"?
Same for the cyclists who pelt down the towpath - you probably know you're being a nuisance, so why do it?