IKEA furniture is about the only thing I bother photographing before taking apart. My old desk had maybe eight different bolt types though, so I get it for complex items. But for a basic ceiling fan or keyboard, it seems like overkill. The baggie-for-screws method has never failed me.
You say the baggie method never fails you, but I've had screws spill everywhere when the bag tipped over. For something like a ceiling fan where the screws look almost the same, a quick photo saves me from guessing which slightly different screw goes where later. It takes two seconds and stops that awful feeling when you have one screw left at the end. Why trust a flimsy bag when you can have a backup picture for free?