I've owned several sets of custom footbeds and have had overall great "success" with them. I do recall needing to have one set re-made because they were causing me pain. My most "recent" set is ancient, falling apart and the edges are eating up my shoes and socks... but I can't swallow the ~$400 for another pair. So I made some.
I casted my feet in an unloaded position and laid up and vacuum-bagged a composite of carbon fiber and kevlar, overlaid with thin neoprene. These fit great and are really comfy! I've been quite pleased with them overall. However, I've noticed back pain over the last week... and only been wearing these regularly for about two weeks. I've had all sorts of back problems over the years (the reason I wear custom footbeds), and at first attributed the back pain to a lumpy bed, etc--then realized the obvious.
When standing with the orthotics in my shoes in a "neutral" stance, ie positioned neutrally as aligned by the orthotics, I've found that rolling my feet inward a little changes the pull (tension?) I feel on my back muscles. As I roll my feet inward (flatten them) I can feel the muscle tension in my lumbar region spreading outward and more neutral, whereas the orthotics focus muscular use toward my spine.
My question revolves around what I pretty much know to be true and what I hope or would like to be true: Any chance my body will just adapt to the new orthotics? Or do I need to remake them with a less-pronounced arch?
As a follow-up, making the cast on a weight-bearing foot and more collapsed arch doesn't make a ton of sense to me. It seems like it wouldn't provide enough support, and the orthotics are intended to prevent that collapse?
Any words of advice from the medical, physical therapy, sports health or kinesthetic community here?
EDIT: A corollary example is new eyeglasses. When people get new glasses, it can sometimes take them several days to adjust to the new prescription...