The Freeze Arrow and Skip Master courses fell defeated beneath my feet in the past couple days. I'm rather proud of this. It took a lot of work to get there. Each is a little over 6 minutes long, 4 songs in a row. Freeze Arrow ends with a 9-footer. Skip Master ends with two 9-footers. Each of the songs in isolation is tolerable. Stringing them together makes it much, much more difficult.
I've noticed that songs I don't know well take a lot more energy than those I do. I'd guess that this is because as I learn the steps for a song I also learn how to hold my body: where my center of gravity should be, which way I should be facing (and usually turning), whether I'm coming up on a section where I can rest a bit (relatively speaking) or whether I have to keep going all-out. Time seems to slow down in sections like that. 10 or 20 seconds can be half of forever. Anyway, the point is that getting my body in the right place brings my feet to the proper arrows almost for free, so I don't have to make sudden and tiring changes to how I'm standing.
There are two or three more courses to complete. One is Jumping, which I've almost got. Another is Boss Rush 1. That's going to take some doing: the last two songs are 9 and 10 feet. One thing at a time.