@fullcapwearer

Southernguy is right. It depends on lots of things.
Shedding could be due to the type of combs & brushes people use, the products they style their hair with or the type of attachment they prefer or even the way they detach and frequency they wash it.

I've never suffered from shedding and I've never had to use a knot sealer, but the last piece I got from a supplier shed in less than a month. I bought two pieces from them and so I'll have to use a knot sealer on the second piece.
I'd be a fool if I didn't.

Certainly a lot of people here use and swear by different methods of knot sealing.
You or I can't say that what they're doing is right/wrong or should/shouldn't be necessary.