So this odd thing happened on my timeline the other day...
I add together two segments of an hour long show, each one is 7-9 minutes long and I'm at about the 25 minute mark of the show. The timecode starts at hour 1. The end point of clip 1 ends with :17 frames, the length of clip 2 ends with :18 frames. So you would think when adding those together your new endpoint would end at +1:05, right? But it went to +1:03, dropping two frames.
I know about thedrop frame increments, although I don't have it committed to heart. But this was the first time I had noticed any funny math within FCP. I had never seen this discrepancy betwen clip length and the timeline before, and the producers with me were freaking out and re-adding everything, because the show had to come in at a set length. In the end a few frames missing didn't matter much. Still, if one had to ensure total accuracy would they edit non-drop frame?