Larry Williams is an interesting guy. I should probably spend more time studying his stuff.
I have always held that the close on Thursday is the significant close, because Friday's price movement represents a large number of traders exiting trades for the weekend. That give a false picture.
I used to use the Williams %R for trading inside of channels. I should probably go back and review it. I kind of dropped that, and oscillators in general, when I started focusing on the relationship between the Bolinger Bands, and the 3 main Moving averages. You can only do so much before your screen is too cluttered to comprehend.