Specific shot testing utilizing natural or artificial slopes (hopefully made to look natural). A championship course ought to expose the most talented golfer. This is not a Matt Wardian statement about risk, reward and penalty but rather a concept that is evidenced in the Philadelphia School of golf but rarely discussed. By the way, I'm all for luck and variables that offer good and bad results--these should be an integral part of the sport. However, some championship courses were clearly designed with a variety of specific shot tests in mind throughout the round.
Take for instance the 5th hole at Merion East. Here is about as natural a landform hole that there is in golf. How were the natural features utilized?
The fairway cants from the right towards a stream that runs the entire length of the hole (507 yards from the back tee). The hole doglegs slightly right to left. The safe shot away from the corner and the creek is to the right where you are left with a ball well above your feet and the need to hit over a large bunker 30 yards short of the green, which slopes precipitously away from you, like the fairway does, towards the creek. The player that properly executes his shot and dares to take on the inside of the turn and play closest to the creek is rewarded with both a level lie and a shot into the slope of the green. All other shots are played with the ball above your feet (righties). The best players can hit a fade off the draw lie and thus are rewarded for being able to execute the shot that is tested--fade off draw lie. Players with less skill can play to the right of the green and hope that the ground will feed the ball onto the green. Otherwise they'll have an almost impossible up and down with double bogey likely. The lesser players playing along the right side of the fairway will have the ball well above their feet. They may be tempted beyond their abilities to advance the ball towards the green but the large bunker short and the stance itself makes that too risky a decision. The smarter player with less skill will play towards the flatter fairway area and play back into the slope of the green.
Huntingdon Valley is a course students of golf architecture (and how it melds with the maintenance practices) should study. It is an excellent classroom in specific shot testing, particularly demanding in terms of shot making and ball striking. Unfortunately, fewer golfers today, partly due to ball construction, can shape a variety of shots. Significantly longer distances off the tee mean that higher approach shots can be made and the need to shape shots is reduced. Softer or more lush conditions mean that balls don't bounce and roll as much as they did. Returning maintenance practices (including widening fairways) and either lengthening or rolling back the ball will bring the equations back into play.