Most skills are things that you can get better at.
I bought a nice fountain pen (well, a $14 pilot) and overhauled my cursive writing. It took about 6 weeks and I write pretty legibly in cursive. I'm more legible in various print scripts (that I have also worked on as an adult), but cursive is faster.
Admittedly, that is just an anecdote. But if you're curious, try and get better... you'll likely improve if you actively practice.
I never liked pure cursive and do a mix, it's more of a print-sive where some letters are always print (F, J, G, Q, a couple others) and others are cursive depending on flow, speed, etc.
I have a bit more practice because I also sketchnote.
Have you tested? I recall - maybe a decade ago - seeing a study suggesting that in fact printing individual letters could be faster; I still write in cursive when I need to handwrite though (basically never).
I suspect it more typically degrades. I always had poor handwriting scores but, over time, I wrote more and more for my personal consumption and speed became more important than style. Arguably shorthand would be more useful for people in general than impeccable Palmer script.
I bought a nice fountain pen (well, a $14 pilot) and overhauled my cursive writing. It took about 6 weeks and I write pretty legibly in cursive. I'm more legible in various print scripts (that I have also worked on as an adult), but cursive is faster.
Admittedly, that is just an anecdote. But if you're curious, try and get better... you'll likely improve if you actively practice.