I quit skating when I was 17, skated here and there over the years, and returned to skating last year at 29.
My consistent jumps were through the double toe loop. I had landed double loops, flips, and lutzes, but never consistent, never at the same time, and never in competition.
I have somewhat regained some jump skills, though I've seen some regression as of late, and can usually land double salchow and toe loop. The other doubles are infinitely harder for me. I also have major air position problems! I'm never tight in the air, and my free leg is always loose- that hip is very open. I get enough height but without a good air position more jumps will never come. I also have a vastly different body than I did at 17- I weigh 15 pounds less than I did, but my lower body is a very different shape (I have hips now!) and my center if gravity has really changed.
At times, as I watch other adult skaters, I think skating before has put me at a disadvantage when it comes to jumps. I subconsciously try to revert to old technique, which does NOT work with this body, and a few of the adults I skate with have great technique and look prettier on the ice.
Talent has a lot to do with it too, of course. Perhaps, just like my first go around, I've simply reached the limits of what my body can do?
I think, no matter when you started, double jumps are hard!