The airline I used to work for did exactly this. 7 flights a day between it's two biggest domestic cities. 0600, 0700, 0800, 1500, 1700, 1800, 1900. The demand is generally concentrated. As for timing I think it does matter in the game because I have one route where my competitor flies more seats than I, but I have 60% of the pax. His flights (on larger planes) are at 0200 and 2100, mine at 0800 and 1700.