MikeCirba,
Replaying Waterville greatly increased its stature in my mind. I still don't think deserves mention in the same breath as Ballybunion and Lahinch, and lies behind Tralee and Old Head in my mind, but compared to what I thought of it on my first visit it certainly moved up a lot. There are probably two causes for this -- it was raining when I played there the fist time and I've never been much good in the rain (I had my first decent round in the rain ever last time I played Carnoustie, only because I decided getting a caddie would insure my clubs stayed dry and I was able to play halfway decently) In addition, there had been some work done on it in the intervening years (between 1996 and 2004) but I didn't remember what was there before well enough to recall if that could account for much of my change of heart.
Likewise I think that Dornoch would improve upon a replay. I played it once in 1991 and while I thought it was a good course, I didn't feel it was in the same category as many of the other links I played on that visit. Hopefully next time I'm in Scotland I'll get up there for a replay or two (perhaps I can get Rich Goodale to join me and point out its charms) Maybe I just didn't "get it" when I was there, or the benign conditions and easy 75 I shot reduced its stature in my mind compared with the sterner tests I faced elsewhere -- I eagled 12 with a driver/wedge, I don't think I should be able to do that on a top course (especially with a balata ball) but in more typical wind conditions I would guess that's not really a possibility.
If I had played Waterville on a day without rain and Dornoch on a day with a good stiff breeze, perhaps I would have rated them higher, perhaps I just wasn't smart enough to recognize how good they are, or perhaps I just differ with the consensus on them (certainly possible, my second visit to Turnberry only reinforced my opinion that it is vastly overrated)
Perhaps playing a course multiple times in a variety of conditions isn't so necessary as playing them once in suitable conditions. Links need wind, most golfers don't like playing in much more than a sprinkle, courses that are waterlogged or severely drought sticken will not show their best, etc. If I had a chance to visit ANGC for a week but it had rained 12" in the week before I arrived and rained an inch and a half every night, even though it might be sunny and warm during the day when I played the course would not be showing itself at its best, and it wouldn't matter that I might play it a half dozen times, I still wouldn't be capable of fairly evaluating it as well as I could with one play when the course is playing F&F as was intended.