Man, a lot of the arguments you are making are not based on anything but assumptions and biases
You have no idea, what casual fans require. In my estimation they require good music. When the music falls off like Wayne did after C3 people were less than eager to check for him. When he was on fire, everything he dropped got played he because it was good
You don't know how long the actual process of making Illmatic took. Useless diatribe
Ja rule didn't over saturation and his constant stream of hot singles is not why he's not in demand now. He was a singles artist and the market responded as such no difference between Ja rule and Fetty wap. When the decline in quality of Ja rule singles fell off, so did he
Missy wasn't overesuation either. She was the same as Ja. they made the most of their run. Missy was a novelty. Neither of their careers were harmed by dropping a lot of music when they were relevant
You are a lazily making the assumption that if Ja and Missy would've taken more time then the music will have been better received
More time doesn't mean better music because we have no idea about what goes into these artist recording process