Yes, if PA goes beyond the X point, the pattern is invalidated. I trade advanced patterns according my trading plan, which includes setting SL. And I usually set the SL levels 5-10 pips beyond the X point. That is how I trade advanced patterns. Other traders set the SL taking into consideration also ATR (average true range) levels... so trading plan can be quite various, as many traders are... :) important is that you backtest a strategy and then stick to it to acquire consistency.
The reason behind my SL setting is that in many cases PA can retest the X point in an advanced pattern and that is on a higher time frame called a double bottom or double top. If you set your SL exactly on the X point, you might miss the reversal from that point. That's my reason for doing so with the SL levels.
I rather call it experience... :))) I was stopped out too many times at the X point in my early/newbie years, then I updated my trading plan to 10 pips beyond X point and so I saved myself a lot of money...
Grab a glass of coffee, open your PC and spend 1 week with backtesting, and you will find out some amazing things that books aren't telling you... ;) that is how you start trading, don't miss the backtesting before you start trading, you will loose a lot of money and precious time... !!!
I'm far away from a pro... :) but I can tell you that I struggled 2-3 years and then I started to learn, learn and learn and to get rid of the bad habits. If you start now to trade, start with learning, this is how you do not get bad habits. You can learn it in 3 months and another 3 months to backtest and forward test a good strategy and then you will find consistency. This is the minimum, 6 months, if you do not want to loose money. ;)