Day of week biases

Someone's telling now it is good going long US Oil in the friday, and going short in the wednesday.
Is Black Monday really worse in the markets? Lets find out in this article

Percent of win report day by day. Yes, Friday is the best day for trading long US Crude Oil, since 1986, but not Wednesday for going short. Good option is Monday, instead. No good days of week for going short on soybeans and sp500, percent win is less 50%...

These biases are not a trading strategy but a good piece of puzzle, not subjective, for more reliable leaping in the markets.

Reports and calculations are generated with Tradingview data and my python engine.