Sure there is, not on an intraday timeframe, but it is there. The big joke is all of these teachers want to make you rich, it takes a real professional to find an edge. It took me a decade, and yes I've worked on a desk. Joe that works as a dentist and trades part time will never have a chance.
Everyone knows moving averages are the real key to success. That's why all the top people in the industry only debate whether to use the 50-day EMA or the 47-day SMA.
If it's quantified, I don't see how one can have different results. If the strategy is all "maybe do this and maybe do that" then it's more of a guessing game and yes, the results will differ.
Most stuff works at the right time and the right place, knowing when it's not the right time or place and not to trade is the bit you can't teach. We are all trying to do the same thing, just we look at it differently.
I think you meant to say if its "automated"...the results should be the same assuming all trade signals were taken by the traders. I agree with you on that. Yet, if its not automated....its basically still discretionary even if its rule-base. Therefore, different traders using the exact same strategy will have different results because they "apply" it differently. Its almost the same reason why some say backtest results had a positive expectancy but real money results was losing. Traders just apply a strategy different when real money is on the line. Thus, when emotions, experiences, expectations, distractions and so on are factored into any given trade...we're all different from each other and will react differently from each other while trading the same markets. Those differences will cause different trade results.
I hear you but if you're not following a rule based strategy exactly to the point, what's the point of the rules in the first place? Backtest results are a completely different topic. Most commonly they don't work in real life because they're curve-fit, have peeking problems in code or underestimate slippage. It has nothing to do with the trader's personality.
Other than the possibility that you may have worked on a desk, this posting is blatantly false. Reader--Joe does have a good chance if he follows PRM.----and there is no such thing as a free trade barring some option spread trade that would have limited upside. This was directed at the poster who was talking about scaling out of trades that did not involve hedging or premium credit.