We can win many times, if we win and lose every second time we stay at the same some level, and it is easier to lose twice in a row than win twice. The parlay we lose some more times than win it. I have tried it some and found it not so good. We last a bit longer than playing martingale. That means we can win but seldom much, a loss is a loss and in near all cases eat all winnings. I learnt i a bit different, we should lose or win twice.
I was impressed by it when I got it, but never succeed using it. On an EC a loss twelve times is not rare, and more will happen.