In games like No-Limit Hold’em then certain strategies can be weak. However many players and certainly at the lower levels are unaware of the weakness of their overall strategy or in how weak their strategy is in certain situations.
Let us look at an example here to show you what I mean. It has been folded around to you in the cut-off seat and you open raise with a very wide range. Your goal is to constantly attack the blinds until you are 3/bet and then you fold all but your strongest holdings.
Now this strategy is fine under one condition and this is that your opponents allow you to exploit them. If they do allow you to exploit them then you are going to make a lot of money over the space of a year in these situations. However here comes the crux of the matter because if you get as much as one single opponent that not only notices what you are doing but is aggressive enough to widen their 3/betting ranges then suddenly it is you that is being exploited.
Let us say that you open raise to 3bb in the cut-off with a very wide range only to then fold 90% of that range to a 3/bet. This is common with wide ranges because there are so many weak holdings in them. So if you fold 9/10 with immediate effect then your initial loss for every ten hands is going to be 27bb. So in the one hand that you don’t fold then you have to make at least 27bb in profit to get that money back! Now there is just no way in the world that your average profit for the 10% of the hands that you play will amount to 27bb.
Some of the time your hand will not be at the very pinnacle of your 4/betting range or your opponents hand has you crushed. Even if you 4/bet and your opponent folds 100% of the time after 3/betting you then you still only win back around 9bb plus the 1.5bb from the players in the blinds. So it is very difficult and almost impossible to win that money back and so your strategy is terribly weak in this situation. Most online poker players never check their strategy in this way but yet it is a vital process of being a winning online poker player.
This is why so many technically decent players struggle to make money; they make money in certain spots and then spew it back in others. These days within the modern online poker dynamic then you are always better off erring on the side of being too defensive than too aggressive. This is because your opponents even at relatively low levels will simply not stand for over the top pre-flop aggression. Also pre-flop strategy is much easier to get right than post flop strategy and this is another problem that overly aggressive play faces pre-flop.