Because not much is happening, the weekly updates are once per 2 or 3 weeks. At this moment the market is bearish. There is still a lot happening on the background (technology). The owners of cryptos are divided in large investors and the small investors. Exchanges are for the small investors and there is a belief that the real value of certain cryptos is an OTC value on the black market.
Large investors can manipulate the market quickly and take a lot of profit from the small investors. If you know the market is manipulated and have the time to OutSmart the big players, this is your change but be careful, even the big ones can loose a lot of money because they play against each other like an online poker game.