For most systems optimal f will be between 15 % to 30 %.For a system which has 50 % success rate and reward/risk ratio of 2:1 the optimal f comes to 25 percent of your trading equity to be risked on each trade. With the kind of mkts we are in,this becomes a way too large .
Trading on optimal f requires that one starts with small capital which one can afford to loose. I dont think most of us can bear the huge drawdowns which is a part of trading on optimal f. Larry Williams trades on optimal f and goes to the Church regularly.
I think about 10 % of equity as suggested by Larry Williams is a good viamedia between our 1 % conservative and 25 % opt f trading !!!
Trade well !!!!