and if by 'system' you mean that every winning player adapts to the table conditions, then you are correct. but thats a pretty wide definition of a system.
now if you mean strategy, then that is different. i like to pick on the weak players as i am sure we all do. isolate those that have shown the ability to fold hands postflop, and are scared by every scare card imaginable. against those players i will play way more hands and take way more pots.
i like to raise pf if first in, its not a system, its a strategy. if you follow a system, you become predictable, and that is bad. what is worse is if you follow a system and win with it, you will be more likely to continue to be predictable at the limits where you will get killed for being so. and that is bad.