Is it neccessary in the Gl2 to record through a tape with the lens cover on to keep the timecode accurate? I know with the XL2 you can use the end button to go to the end of the last shot. Help appreciated.

No. Just be sure you start new recording over the very end of the last bit of recording, especially if you have taken the tape out of the camcorder for some reason, or reviewed footage you just shot. The rec search capability helps do this manually. In normal shooting this happens automatically if all you do is pause between takes.