I don't think it's mainly with Supervised mode in mind, though I haven't managed an environment in that way myself. That being said, I think "payload" is the wrong way to say this; think more along the lines of one "goal" or "problem" per profile. For example, if you have the goal of automating WiFi or VPN, but that requires a user-based certificate in your environment, you're up to two payloads by necessity for that one profile (Network or VPN, and SCEP). But that's a little nit-picky.