not necessarily Numbertea, I could back test my system up to 2011 and then forward test on out of sample data, which would be 2012 and 2013 say. If it still stacks up, then I'm good to test on demo. Thats how I prefer to back test which is why I disagree completely with the original thread.
What you do there is out-of-sample testing, which means you have 1 dataset to optimise your strategy and then 1 dataset to test your optimisation approach.
This is ok, better than a backtest at least.
But are you aware of the fact that you judge the future performance of your strategy based on only 1 datapoint? (in-sample as "past data", out-of-sample as "future data" => 1 datapoint to judge live trading)
A good Walk Forward Analysis can give you at least ~100-150 datapoints to judge from. The approach stays the same, but the results are more reliable as you view a larger part of the picture
So even if you disagree with my post, its a matter of fact that a WalkForwardAnalysis is just the way you do it - but one step further
Perhaps this convinces you to give it a try, at least