Yes, Non-Destructive Testing is generally preferred (with all
I believe that slings (and indeed ropes, and all the rest) are simply checked by examination. But (if I were doing the job) I think a system of changing them by date (or date code) similar to current practise with high-pressure anaesthetic hoses might be prudent. But even if slings (chains, etc.
) are "in date", that doesn't mean that they shouldn't be carefully examined, of course.
All a bit time-consuming if done properly. And there's the rub:- most "contractors" that I have seen doing this stuff have come in, bunged the stickers on, and disappeared before you knew it. With the bill to follow later, of course.
In the UK, just like PAT testing, CORGI gas inspections, annual vehicle inspections (so-called "MOT's") and all the rest ... Regulations like this usually end up as a "licence to mint money"!
Lots of stuff about LOLER
on the web, of course.