Flat pack furniture traditionally had the relationship for being crap, in particular for missing pieces like a screw here or there, but when Ikea came along they did things properly. That was the reason they got so popular, they were so much better than the competition, and they forced others to up their game. I think they were the first to actually include extra screws, to cover the occassions when they weren't there, but these days their quality assurance is so good they just include the exact right amount every time.