i do not wear mine 24 hours a day since i have to go to work mon-fri, but aside from that i wear mine "all the time" for years now. my neck is just as strong now as it was before like in high school or whatever. it's not like people go around trying to lift weights with their head anyway, lol.
after all this time there has only been 1 noticeable change, and that is my adams apple does not hang as much as it used to. when i first started wearing the colar it was very hard to swallow because the adams apple was being pressed on (and i have always had it on its tightest). after all this time "it" has learned how to pull up and stay more or less out of the way and i have no troubles eating or drinking with the collar on. you can still see it like in that picture over there >>> unless i've changed my profile picture since this posting. it's still there but hardly as pronounced as it used to be.
this is an after effect i am more than willing to deal with since adams apples are not very feminine anyway. i am sure if i stop wearing the collar for a year it would drop back down, but why would i want to do that? its so cozy.
if you have to go to work like me, and you sleep in the said collar, make sure you have at least an hour and a half so you can take it off before going to work. if you don't people will wonder why you have these weird lines around on your neck.