We have been lucky withour assessor. We had one just after we took over and then another 12 months later (6 months ago). We asked hime why so soon and he said it was to bring us into line with the new system. We passed our 3.5 stars without any problem. He was very approachable and his comments were fair.
It is also part of our lease agreement that we maintian our star rating. Im not too sure what will happen if the next time round we need to do major refurbs etc to kep our rating.
I do agree the "star system" is almost outdated what with tripadvisor and the customer review sections on all the OTAs!!