What percentage, though? A typical teaser starts in the middle of action, for dramatic reasons - or then with a Captain's Log explaining the mission of the week and also stating that the interesting part is just about to begin. Both would fit the concept of the A-team having been summoned to the bridge before the cameras got rolling.
(Then there are episodes that start out "softly", perhaps following Picard sipping tea in his Ready Room or Riker doing a holo-adventure of some sort. In those cases, we can argue that the bridge is actually crewed by the B-team at the time, and the main heroes rush there only when Picard gets abducted by the Slimy Space Slug or Riker reports that the holodeck has started turning people into memory crystals. That's reaching, sure, but the "soft" starts are actually in quite a minority in TNG at least.)
Timo Saloniemi
(Then there are episodes that start out "softly", perhaps following Picard sipping tea in his Ready Room or Riker doing a holo-adventure of some sort. In those cases, we can argue that the bridge is actually crewed by the B-team at the time, and the main heroes rush there only when Picard gets abducted by the Slimy Space Slug or Riker reports that the holodeck has started turning people into memory crystals. That's reaching, sure, but the "soft" starts are actually in quite a minority in TNG at least.)
Timo Saloniemi
