Quality and quantity are both important, because "quantity makes quality".
I don't agree with you on this and I don't think quantity actually makes for quality as I've seen very short post that contained Alot of quality and even earned Alot of merits as a show of appreciation for it's quality.
I'm practically not against lengthy post especially when there is actually a need for it and I also agree with you that the case usage also matters Alot when talking about quality and quantity.
Talking about JayJuanGee, I think we all know he doesn't just make random post but rather takes Alot of effort and time to put out a post and his exceptional.