This mistake is easy to read and understand here, yet martial practitioners still suffer greatly at the hands of the radical and different. Conventional warriors suffer at the sneaky ways of the guerilla. The rule-abiding cop fights the no-rules bad guy. Kick-boxers suffer at the hands of ground fighters. Wrestlers suffer at the hands of ground n' pounders.  Firearm-range, paper-target shooting champions suffer at the rabid, trigger finger of the alleyway thug. The boxer never sees the hammer fist. This bloody list of interdisciplinary mistakes is almost endless. Train to fight the enemy you expect.
     Second, remember not just to train in a multi-disciplinary manner but to fight against these so-called, "rookie/wrong-ways" of common attack. These are  high-percentage probabilities. 
     Year-after-year your fighting system, your rules of engagement, engrains itself into your muscle memory. You become use to the lines and methods of hand, stick, knife and gun attack that your system delivers. Then someone spits in your eye and hits your head with a frying pan. Wait now - what belt level was that again?