David:
I know a bit about it.
But mostly just from observation and interpretation. I don't think anyone has really studied it.
Sand topdressing has always been done on courses in Britain, to keep the fescue greens from developing too much thatch. Everyone from Old Tom Morris to Tom Simpson to Walter Woods has been much quoted on the subject.
In the States, some superintendents have been proponents of topdressing going back for ages, but the USGA Green Section really started promoting the practice in the mid-1980's ... one of my mentors in the superintendent business, Tom Mead, quit Crystal Downs because his green chairman insisted upon a sand topdressing program that Tom thought misguided. So, for the last 25 years, well-heeled courses have been adding 1/4 to 1/2 inch of sand per year to their greens, on top of what they fill the aerification holes with.
It does start to add up. On many classic fallaway greens, you can see now that the front of the green is built up 3-4 inches before they start to fall away. That's all the topdressing sand ... originally a bit of the approach would have drained through the green. Does it make a big difference in play? Mostly on chip shots from the perimeter, and on marginal approaches.
Do the green contours change in the process? Yes, if it's sloppily done. Plus, on hillier sites with elevated greens, there seems to be extra topdressing at the fronts of the greens which makes the approaches very steep and wrecks the ability to play low shots into the front hole locations. I saw a lot of that at Cypress Point the last time I made a tour of it.
How much can things change? Well, to me the classic example is Yeamans Hall. In the 1930's, they reduced the size of the greens to save $$ on the maintenance budget, but because the greens were common bermudagrass and quite slow, they topdressed heavily to give it some speed. By the time I first saw it, the smaller area of the new greens had been built up twelve to fourteen inches from original grade ... it was like a mushroom was growing out of the original green. There was no hint of the ridges and swales which were on Raynor's plan of the greens and which presumably had been buried underneath all the topdressing. When we rebuilt those greens, we took the sand and spread it out over the entire pad for the original greens, but we had to look back to the plans to get a sense of what sort of contours to restore.
Pinehurst, of course, also had common bermuda greens for many years, and I would guess they are built up just as much as Yeamans Hall's greens were. They carefully mapped the greens circa 1980 and have tried to preserve them since then ... but that would be like preserving the old mushroom tops at Yeamans.
Is topdressing necessary? You have to combat the buildup of thatch and organic material ... you can do so either by topdressing, or by aerifying, or the combination of both. Golfers don't like aerification because the greens are bad for a couple of weeks afterwards, so the reliance on topdressing has increased in recent years.
P.S. No course I know of topdresses more frequently than they do in Bandon ... but in Bandon, they topdress 20-30 yards out away from the greens, so the buildup shouldn't come into play, except around greenside bunkers which become deeper as the turf around them rises up.