We do this where we are moored. When I am off cruising I am quite happy for my mooring to be used. My neighbour is currently away for a few weeks and is using someone elses mooring and is quite happy to have his used by others. Our CRT mooring manager is happy with this arrangement as long as we text / email to let him know. We do also have short term moorings here, but during busy times it can be difficult to moor near the facilities and personally speaking I enjoy seeing new faces. However, I am aware that not everyone feels the same. I have seen other long term moorers near me moving visitors on and not allowing them to moor up. Not wanting to start an arguament here, but the people that do tend to have a problem with it near me are the ones that I have never actually seen move their boats.