Sequels and continued stories have their place. I like getting to know characters and what they are like. In erotic fiction, you tend to need more then one part to do that. So I'm all for long developments (and those readign my stuff know that I use the word long in it's truest sence 🙂 So multi parters are a matter of taste. They also represent an investment of time for new readers.
On the other hand, fast one off tales can be great. They can provide striking images, get in, and out of a senario fast without extra baggage, and provide the reader with what they are looking for.
There are places for both 🙂
Myriads