We all have skills/habits that just take longer to learn. Pullups, the habit of saving, heck just getting to the gym. I have at times been embarassed by how long I have taken to become more consistent at double unders. It has literally taken years. Took almost a year to get the first one.
Since that first double under it has been a journey that has taken years. I have whipped myselft plenty of times. I have lost them at times or at least had workouts that were slowed down considerably because I kept missing. I have even gotten really frustrated during a workout, that was memorable and that very rarely happens for me. I still kept working at double unders though, not everyday. Certainly at times weekly or at least a few times a week, and don't forget it has been years. I have tried lots and lots of ropes. I have combined double unders with other skills that I want to improve. Recently I have jumped roped almost daily due to limited time for workouts. I have coached others through the process and that has helped me tremendously. Helping others helps you, more on that another time.
I have gone from consistently inconsistent to understanding how to become more consistent at least for double unders longer and shorter duration workouts. Double unders I tackled without a coach and I have also learned that I could have sped up the process with a good coach. I also have more fuel to conquer myself. I have gotten better at running. I am able to jump rope daily (short periods) now for weeks at a time without knee pain and foot pain, as always technique matters(really matters footwork, hand position, core engagement). I have sped up my goal to get 100 double unders in a minute. I have broadened my horizons for fitness with a jump rope.
See a challenge through especially the bigger challenges. The harder lessons are the most lasting, memorable and most transformative.