Hi Mark,
Interesting subjective question, which I'm sure will evoke various different objective answers, from a range of respondants.
I'm sure there's a minimum amount of time any architect would like to spend on site. As to how far in excess of this one goes, would vary wildly IMHO.
It would have to vary with the eventual course quality, the type of site, and the size and skill of the team with whom the architect closely worked, as well as the philosophy and work ethic of the respective architect.
I do know that the Doonbeg site was up front in Norman's mind, for a long time. He was talking about it years ago, and unreservedly said that it was the best site he'd worked on to date, and that it may in fact be the best site he'll ever get to work on. I believe he meant this, and didn't just pump up the site for marketing purposes. He said the above in a small personal gathering while at another course site in Australia.
However long Norman spent at Doonbeg, the results speak for themselves, with the course being excellent, from all early indications ...
I find it interesting that Norman is reported as visiting Doonbeg 27 times. I regularly play a Greg Norman Design (GND) course, and could confidently say that he was at the site on significantly fewer than 27 occasions. I do know however, that his design team, most noteably Bob Harrison, virtually lived on course, for a long, long time.
No doubt, many GND courses bear small touches from Greg himself, while others may be primarily his own work.
Consequently, this too must have a large bearing on how many occasions an architect finds himself on site.
As many Aussies will attest, MacKenzie spent extremely short times on some courses, and the results in several instances are sensational. That's gonna throw a wrench in the works for this post...
I'm very interested to see what others say. Good stuff Mark !
Matthew