Think of a traditional martingale chart. It is a smooth exponential rise to the right then a sudden immediate drop to zero. The goal is to get in and get out and do it again. Imagine you were to take scissors and clip out a small portion of that graph that represented just 100%.
If it was that easy, we wouldn't be here discussing anything but rather enjoying an easy life.
I think the key point is, how much you are willing to risk and eventually lose. I mean, doubling your account is difficult, but possible. But doubling your account 10 times, without blowing out... Still possible, but so improbable, that it might not be worth seeking.