Sean:
NGLA's 6th sure did have "sleepers" supporting the surrounding bunkers on that hole early on.
In my opinion, the use of, and fact of sleepers in golf and architecture betokens, in a general sense, the entire evolution of golf and architecture-----eg how much it has changed in its 150 year existence and why.
Why were "sleepers" used early on in the Scottish linksland and on golf's earliest courses? Aren't the reasons obvious? Sleepers were perhaps the most fundamental (and rudimentary) example of how form followed function in the earliest days, and in the earliest examples of man-made golf course architecture.
I'm quite sure the use of sleepers was more prevalent in early linksland architecture for the simple reason that most linksland sites are predominantly sand-based and consequently many of the old dunes bunkering and such was just naturally more unstable than what was found in this country early on (mostly inland sites of greater clay/loam sites).
So what was the simplest way to stablize unstable bunker and dune areas? Obviously with wooden boards (sleepers).
The fact of their use at early NLGA shouldn't be surprising for two basic reasons;
1. NGLA is predominantly a sand based site.
2. Macdonald was dedicatedly copying some GB holes and hole concepts (obviously including the look and materiels of some of their early man-made architectural features).
But it's not all that difficult to imagine why "sleepers" eventually when out of fashion in golf course architecture and became far less prevalent;
1. They were contrary to the push for more "naturalism" in golf architecture, as it's pretty hard to deny they do look unbelievably artificial for the simple reason THEY ARE.
2. They could be quite dangerous to golfers for the obvious reason of balls richoceting off of them.
However, golf course architecture has not had many "renaissances" in its 150 year history (until recently
) but one notable "renaissance" maybe forty years ago was the basic reuse of the "sleeper" concept.
Who regenerated that idea? Well, Pete Dye, of course, with his prevalent use of railroad ties.
And why did he do that? Bascially because when Pete and Alice went to Scotland years ago to study the linksland and its architecture they were as fascinated by some of the crude and rudimentary original aspects of early linksland courses (Sleepers) as they were with the inherent naturalism of other aspects of early linksland courses.