[holdem2000]

For me the reason I rarely mix up my PFR size is because I'm playing so many tables, it's a lot easier to just go with a standard amount. This not only helps speed up my preflop decisions but more importantly allows me to very quickly decide how much to continuation bet after I've decided that I want to.

Varying your raises, if executed well, is certainly a better strategy, but when playing more than 4 or 6 tables it becomes difficult to actually execute well (even if playing one table, the strategy still requires the dedication of a significant amount of objective thought to make sure that indeed your play is sufficiently mixed up to still disguise your hand).

One other objection to variable raises that is probably similar to the first: when your raises are constant sizes you can better estimate what ranges your opponents put you on. Players cannot read false patterns into your betting patterns when it is obvious that the only pattern is you bet constant amounts. Humans are extraordinarily gifted at discovering patterns in completely random sequences of data. If you play with a variable raising pattern many opponents (especially weaker ones) will be under various mistaken impressions that different sized bets have exclusively different meanings (while this is true in some sense, they will take it far too far, believing, say, that all your min-raises are AA/KK). This is generally a good thing, we want our opponents to miscalculate. However, denying your opponent the chance to make this sort of mistake allows you to better estimate the range/hand which they put you on. This is only of much use if you're being lazy as the author puts it, or if you're playing enough tables that you don't have the time to analyze each hand in full detail.

By betting a constant amount we can better stereotype our opponents' thought processes. We eliminate a whole dimension from the possible situations we experience... we repeat the same scenarios more, and as a result are able to vastly improve our intuitions in these limited scenarios (thereby reacting to hands quicker and being able to play more tables). We limit our options, but we become very proficient at maximizing our wins with the style we adopt.