Disclaimer. It is more than five years since I read a Harrington cash book and I no longer have them to hand. I'm working from memory, so if there are any errors below, please go ahead and flame me.
Quote:
Almost everyone here always says Harrington is outdated, but can you elaborate and explain what exactly is invalid?
"Exactly" Nope, not without a wall of text. But I'll give you one quick example. If you follow Harrington's advice on cbetting, you'll end up cbetting at far too high a frequency for modern
online NLHE. You might get away with that at nano stakes or during peak fish hours, but if you are battling regs at any meaningful stake, you'll get exploited all day long.
Harrington's advice on cbetting focuses on flop texture and villain tendencies.
A modern text cbet advice will focus on balance and combo selection. Crucially, it will also focus on balancing your check/calling range with stronger hands (hands that Harrington would have you cbetting). So you end with a much lower, but much more balanced cbetting freq.
Just a tiny, simple example to try and be helpful....there are people on here waaayyyy better than me at explaining this sort of technical detail.
Finally, I bolded "online" because this is fundamental. In a low stakes live fish fest balance will be the last thing on your mind.