I disagree with having multiple channels. As a disclaimer, I have three channels as a result of my evolution over time on YouTube, but the other two are not being used anymore.
Think of it this way - a TV channel specializes in a category of content with multiple programs under it. But they are all mostly related in a way. For example, HGTV is a network about the home and gardening. Mostly it is reality-based now (as most TV is) with a billion variations on House Hunters, etc. But there are also fixer-upper shows, home decor shows, gardening shows, etc. There are also shows about celebrities' homes.
Translated to even a gaming channel on YouTube, you could have a Minecraft Series, an FPS series, a talk show about upcoming games, and a vlog that revolves around you, the gamer's, life. They're all different programs, but they are centralized under your personality (since YouTube channels tend to be of a more personal nature featuring one main presenter) and your genre of video. For this reason, I don't see multiple channels as necessary. There are ways to successfully mix content that becomes consistent with your identity and your brand. That is why I believe YouTube created the One Channel format - so these different types of things could be presented by a creator in one place in an organized fashion.