Having been peripherally involved in psychometrics I found this post Is the Ultimate Test in Golf Unreliable interesting:
"... here are the correlations for the four rounds played at the Memorial Tournament two weeks ago. Basically these correlations all hover around 0. There is no evidence here that the rank ordering of participants from round to round has any appreciable level of stability. And yet $6 million of prize money was doled out on the basis of this selection process."
However, in order to be conclusive, this exercise needs to be repeated for many tournaments or at least a series of tournaments, e.g. all USGA or all LPGA. The post also shows correlations of rankings rather than correlations of scores which I think will make a difference since the test-retest reliability involves actual scores rather than rankings.
Recall that rankings for the top 10 at any end of the day may be separated by only very few strokes so it is possible for someone to score the same score on two days but be at very different positions of the ranking.