If the beads are badly strung as in going to break, or are nice beads but strung badly and with a cheap clasp I restring. Also if I want to wear it, I have no problem redesigning to fit my aesthetic, though as someone pointed out- if it is really valuable "as is" I might not alter it. But a well designed (or redesigned) and well strung beaded piece should mean added value I should think.

Also to protect certain more delicate valuable beads I will restring and put in spacer beads just so beads won't "klonk" together, chip or otherwise get damaged. And it is good to TRY to use a certain type of stringing material such as silk with knotting in between for pearls, or a thoughtful material that "makes sense" in context- as in synthetic or genuine sinew in some Native American type necklaces.

To me the hooks are also important, as nothing brings a necklace down like a cheap barrel screw closure, when a simple or interesting handmade (or vintage) closure would make it all the more beautiful. I like handmade "S" or "J" hooks for most necklaces and especially bracelets as they are easy to use one handed. But using beads and loops as closures is also a favorite.

Wear it and Enjoy!