I gathered some complex body part sections into groups.
This makes that in the timeline I won’t see anymore the group’s content’s master pegs at the top level of timeline’s hierarchy.
This can be resolved by RIGHT CLICK on layer->Show->Unticking “Show Groups”.
So far, so good.
Unfortunately, this also hides the deformation chain groups, which is not very handy.
That’s why, I think that it would be cool, if there was a way to determine for every group (or even every layer?) if it will be shown or hidden in the timeline.