All these theories assume a return on investment and focus on returns rather than theoretical models! In practice, things always turn out differently than you expect.
@DonkeyInvestor You can create a thousand clever Excel spreadsheets and come up with the most elaborate plans! I wouldn't waste my time on that! I use my time to watch the game and try to understand what's going on. The result of that is your return; the result of an Excel spreadsheet is just an Excel spreadsheet and the belief that you’ve done something to boost your return.