These are all none-sense. You only should reinvest your profits if you are sure that you consistently will be profitable in future. Suppose you reinvest continues for 4 years, and then on 5th year have bad result, you are fucked up. Stick to fix account size, and remove the profit to the bank.
Nobody knows for certain if they will be profitable tomorrow. If I didn't think I had a reasonable chance to be profitable then I would not be trading. My objective is to grow my trading account the best I can without blowing it out. Since I have a seperate source of income for living expenses it makes the most sense to reinvest all my profits.
Have you asked yourself what % of traders go busted using this technique? They know traders usually like to hear the sweet stories only, and rest will be covered.
Oh I know. And the majority of big traders who are still on top have blown out on more than one occasion using that strategy. I'm more risk adverse, so I will probably will never do it that way, however I won't say that it is none sense because it has made some traders a fat load of cash. "Market timing is a none sense strategy that does not work" BuyAndHoldGuru.