For the longest time I had, what I thought, was a built in excuse for not being able to do double-unders. Until I saw another amputee rocking them out like no tomorrow, I thought I was going to be stuck doing single-unders forever! Now, let me be clear, this has not made a difference in how I look at the double-under. I hate the exercise. I am not a cherry picker of WODs but I will take a rest day when I see double-unders on the menu. I simply don't like them.
Most of this disdain is also my reason for not practicing them regularly. But another issue I have always had is with "scaling" the double-under. Now, I say "scaling" with a mouth load of sarcasm. In reality, it's punishment! In every gym I have ever been in, the scaled option for the double-under has been 3:1 singles or, in a rare case, double-under attempts. I don't get it! Am I supposed to get a double under faster because I have to do three times the as many singles as my peers have to do doubles? Other than building up stamina, all it does is frustrate and alienate those who don't have double-unders. I can tell you that my problem with the double under is timing and rhythm along with some mechanic issues (I have a hard time relaxing). A million single-unders won't help that.
One of my coaches once told me to practice single-unders until I can sustain 3 minutes of singles before I move on to double-unders. He also told me to practice the power jump to make sure I am gaining height on the jump and not donkey kicking. I think this is a better plan for building to double-unders than the "scaling" that we typically get punished with.
Think of this in terms of "Annie"
Other than building the stamina to jump, doing that amount of single-unders has no mechanical advantage when preparing to do double-unders. It doesn't prepare you for the mechanics of whipping the rope. Better scalable options, and ones I was given during the time I spent at CrossFit Reston in Virginia are: double-under attempts where the counted reps are a successful double-under (think single, single, double or single, double) Or an equal number of single-unders with the jumps being a power jump (higher elevation).
Stop punishing athletes who cannot do double-unders! Help them achieve the double-under. (Of course this also requires us to practice, we know that!)