When flying across the Pacific (and, I assume, the Atlantic), it appears that many of the flights operate within a few minutes' time of each other.

For example, from LAX to NRT, the UA and NH flights leave within minutes of each other as do other flights. The BR and CI flights to TPE also leave within minutes of each other.

I realize that departure/arrival times are timed for best advantage, but is there any other benefit to scheduling flights this closely to each other?