sure you can, if you combine it with a timeout and/or a way for users to break a lock (and then of course, blocking the original user's session if he comes back

sure you can, if you combine it with a timeout and/or a way for users to break a lock (and then of course, blocking the original user's session if he comes back anyway) at least you don't have to wait for the timeout to expire if the user properly closed the application/website, which happens most of the time