It's great to hear that you enjoyed replaying the mine shaft! Actually, they're supposed to be played several times because there are so many gems and seals in them you can't possibly collect all of them in one go. You might also notice how yellow gems are better collected when falling while blue gems are easier to grab while wallrunning. Once you reach the Shrine at the end of the chapter, you'll also unlock time trials and boost barrels in the mine shafts! Let me know how you like the rest of the chapter!