Race the Clock 100% is actually impossible.
If you recall the level Cliffhanger (level 14 or 15), there's an issue. The level requires you to roll the marble around the circumference of the playing board, and then enter the maze from the upper-left corner. Once you get to the upper-right hand corner (on the second layer from the outside), there's this one ruby gem in a nook with a trapdoor. However, the passageway for this nook is actually narrower than the width of the ball. I've tried a few things, like slamming the marble into the gap to try and squeeze it through, and even quickly tilting the board so that the ball might "jump" off the surface, which of course didn't happen. So, unless I'm completely oblivious to some stupidly simple solution, I don't think this run is possible unless we disregard this gem.
Hi. Just wanted to point out that I think that the 52 hole category is 54 holes long (12 each for Old West, Classic Carnival, and Outer Space + 18 for Long Island DLC), and should therefore be called "54 Holes / 100%" or something akin to that.