Every trader I've ever seen or heard professionals even always talks pretty much about using fixed percentages of their account balance in each trade. Also have read a lot of people have used the Kelly criteria to bet or invest with to great success which in some cases can mean betting huge amounts of your account each bet/trade. While I don't dis believe you about your claim about reinvesting profits it would be really interesting to see your theory behind this and why using an amount slower than your profits is the best method to use.