There is another possibility you have to consider. That you do not understand how professionals trade even if they explain it to you. If you risk a constant 1% at every stage to make 1%, for example, then after trade 5 the bankroll is increased by 5% but you lose only 1% at trade 6, although you have 32 contracts. The contracts are increased in an effort to try to capture the winning move as fast as possible. This is a technique of essentially moving the stop and target tighter at each stage while keeping risk and reward constant. Conversely, when you have losing trades, you decrease the contracts but you increase the risk per trade so that when things turn your way, you recover the losses with the least contracts. You need balls to trade like this and big money. This method by itself can become an edge if you know what you are doing. Most people don't.
I see exaggeration in that example, but idea behind it contains significant wisdom. I myself always increase size when in a winning streak and cut it when in a losing one. I see it as one of the key elements of correct money/risk management.
Double up your position everytime you win? that is stupid. double position = double risk! If your Risk/Reward is 3/6% and you double the position you are now risking is 6% of equity on the next trade, and 12% on the next, etc.. You are guaranteed to blowup.
You can double up your position and retain the same risk percent by moving the stops. Many noobs do not understand how this is done. This paper has the formulas you can use for both point and percentage R:R to calculate stops for constant risk percent when you change position size: http://www.priceactionlab.com/Literature/PositionSizing.pdf
this trader must be discretionary. And if so, psychology is important part of decisionmaking.. If method captures major swings, then size is not an issue. Why would someone trade years and years 70% win system. Answer is because it cant be scaled up. So, if capturing major swings only then you set size to maximize YOUR performance. 1% risk trading discretionary,l you lose attentioon too quick as it is hard work. I like reinvesting all profits in next trade. That keeps me alert enough not to get mediocre.
One cannot double up size every time simply because of the margin requirements (assuming size on the first trade in the streak was already decent). With one exception: if every winning trades yields enough to seriously increase account equity. But in that case doubling the size will not make the risk in percentage terms too big, so that still sounds like a solid approach.
In the movie floored one of the ex floor guys said the same thing. I'm paraphrasing but he said that most people didn't get this game - when your right bet MORE