It depends on what your use case for the dashboard is. If the dashboard is meant for constant display, then yes, too many panels is a bad user experience. On the other hand, if you're trying to create a "Oh my god something is wrong in production right now, show me everything so I can see at a glance" dashboard, I would rather scroll than jump between 3 tabs because of "aesthetics".
Aesthetics? How about ergonomics? In the same vein as "alert fatigue," having too many panels on a dashboard (or too many lines on a graph, etc) can overload the user, and obscure the real issues.
> show me everything so I can see at a glance
Yes, exactly, at a glance, not after scrolling through five pages. With careful dashboard design, you should be able to see a problem area actually "at a glance," and then drill-down to pinpoint the actual cause, faster than you'll find it scrolling through a single large dashboard.
I admit this is something of an ideal to aim for, and it can take a lot of time and effort to achieve, which may not be available. However, it will pay off in the "Oh my god something is wrong in production right now" scenario if you can take that time.
