I am going to refer to the Ring of Regeneration. "old school version" starts working after 24 hours. As long as not taken off it works and regenerates even if your killed, as long as it isn't taken off your body. Arm/Leg cut off hold appendage to cut half and it will reattach.
"3.5 version" Same but slower (instead of a turn, it is an hour), but with no 24 hour waiting period stated. (At least as I can find)
I agree with the books no to skill points, those are earn through practice and application. The bonuses however represents how clued in you(or how quickly you understand a subject, skill) are to each skill by the ability bonus. So those I do allow.
As for Spells, I do allow after 24 hours, to study, pray or comprehend your new found power. Because the bonus is permanent as long as it isn't taken off.