My opinion: less frequently is better. Digestion is a major drag on all systems while it's running, and giving it a rest allows the whole body to repair and recalibrate itself better.
From self study, I think that three meals within an 8 hour window, followed by a 16 hour fast, is pretty close to the sweet spot. I'm not quite there yet myself. On most days, I go for one big, long meal at the end of the day. On weekends and other days, I tend to have a very small breakfast, then normal lunch and dinner. I'm trying to find the best pattern for my particular lifestyle and appetite.