I suggest that we use a single lot size until we have a 500% free margin. In this case we can increase our lot size but make sure that our free margin does not decrease to 300%. Because once our free margin drops lower than 300%, chances are we will get MC if we are not careful. Since multiplier size is a huge multiplier to incur huge losses and if you've traded with a lower lot size, you'll be surprised how quickly you get a mc when you double your lot size. Multiple doubles - multiple benefits, yes of course, but you have to remember that it doubles the risk as well and if you do not have good analysis, you may suffer double losses as a result. So we have to be careful if we want to multiply it, make sure your margin is enough to accept double risk.