Doesn't this make victims amongst people who are doing your cache in the decent way? What happens regularly with me, is that I get stuck somewhere (either a WP is missing, I misread stuff, can't find it, all kinds of everything can happen that can make life difficult), find a bench, look really good at what I might have done wrong, and how I can try to find back the right track, possibly missing a WP but at least finishing the cache as it was intented.
I suppose this is handled in good manner? If so, this might be a decent solution.
The only thing it doesn't stop (of course, since nothing stops that behaviour) is people who take a trip and log for a few friends as well. (Which is happening here in my country, or at least I have serious suspicions that it is happening)