Poker systems

I was just wondering if anybody used any kind of systems to regulate their play and if so which game and which system.
The reason i asked is that a couple of months ago i read an article by a
Prof. L V Williams who devised a system called the calendar system to regulate your play preflop. Its simply grouping hands together under a calendar month with an instruction on how to play each hand at any given position. I understand that most all players should know the 6 or 7 best starting hands but this system seems to give you greater discipline preflop therefore avoiding certain hands in BB which may cause you some problems. What i find is that my % of flops seen is greatly reduced which as many people know is one of the most common mistakes made by new players by playing too many hands. The only problem is that i can get so embedded in it that when it comes to the point when more plays should be made i.e in later stage's that i find I'm still too tight.

The problem with systems is that they tend to be, by definition, quite regimented (eg 'do this in this situation', 'play this hand in that situation' etc).

Having a system isnt necessarilly wrong (it is generally good in fact), however you must mix it up enough that you dont become an open book. The easiest person to play in the world is an ultra-tight TAG with completely regimented position and strength based valuations. Some players might as well play with their hands face up.

In short, mix it up, mix it up, (but dont deviate wildly from your game/system just for the pure sake of it)