I feel that I have to point out here that even if you only play 40k and just one army at that, doing so for several years, then, reading comprehension aside, you should definitely have a clear and comprehensive understanding of the game and it's rules. However, for those of us with 6-12 months of experience under our belts the mistakes that can be made are legion; especially when the elements of time and pressure are involved. Comprehending the rules and being able to execute them continuously for 3 hours without mistake are two totally different levels of play, in my opinion. Whether that makes me a 'filthy casual' or a 'padawan learner' I'm not sure but neither am I too concerned. The game isn't going anywhere anytime soon. The mountain will stand, the snow will fall.