Ulrich
I don't really rate courses (for myself) based on what is best. I rate based on how much I would like to return or as a snapshot recommendation for others to use. Hence, you will not see anything about shot values blah blah blah in my system. I will say that I am not terribly concerned with quality because nearly all the courses featured are good to great and self evidently so. So there isn't a point in trying to decide which courses are best unless its for a bit of fun or in the hope that some new light may be shed on a subject. Other than the course itself, I do, however, evaluate things such as price, clubhouse, history and setting; issues which matter in terms of deciding to visit or return to a particular course. I would say the split of course/beauty and non-course stuff is about 60-40.
So it is very possible for a course to be not as good as another course, but I rate it higher because of non-course stuff (usually great value) or even because of a few holes which really stand out. For instance, I don't believe in the slightest that Worlington is as good as Rye, but I do think Worlington's charm, great value etc combined with a very good course make it a 1* just as is Rye. In other words, Worlington is plenty good and distinctive enough even if it lacks the wow factor. The lesser quality of the course compared to other great courses doesn't reduce its appeal.
As another for instance, there will be some courses which are good yet not terribly distinctive and/or poor value or simply not as good as reputation suggests...so my rating my not be as high as the quality of the course may suggest. I would say a place like The Grove fits this description. I wouldn't recommend the course based on the full whack, given the alternative choices available.
If a course earns less than 1* I usually don't bother with the 1 digit rating, I let the readers decide for themselves. However, I do have a map (similar to yours) which tracks the exact GB&I ratings which I do update when I revisit courses.
As you can see, simply because a course doesn't earn a star number, doesn't mean it isn't very good and a worthwhile visit.
3* Don't miss for any reason
2* Plan a significant trip around this course
1* Worth an overnight detour
R Worth A Significant Day Trip (no more driving than it takes to play and have drinks)
r A Good Fall Back on Course/Trip Filler
NR Not recommended
North Berwick, TOC, Merion and Sandwich are my 3*
Kington, St Enodoc, Old Town, Lahinch, Ganton, WHO, Prestwick, Deal & Sunny Old are my 2*
There are bunch of 1*.
Ciao