If you are talking about 4 hour meetings of collaboration, then you are creating something together. And while it's quite often more efficient to see a distilled version of something rather than going through all steps as it's developed (kind of like reading a review article in a journal as opposed to all of the original research), the problem is that you need to go through that original stuff (the 4 hour meeting) to get to the outcome. If you aren't participating then you aren't helping create that information.
On the other hand, if you are talking about 4 hour presentations that can be distilled to 15 minutes of actual value, that's a different problem entirely.
If you are talking about 4 hour meetings of collaboration, then you are creating something together. And while it's quite often more efficient to see a distilled version of something rather than going through all steps as it's developed (kind of like reading a review article in a journal as opposed to all of the original research), the problem is that you need to go through that original stuff (the 4 hour meeting) to get to the outcome. If you aren't participating then you aren't helping create that information.
On the other hand, if you are talking about 4 hour presentations that can be distilled to 15 minutes of actual value, that's a different problem entirely.