IMHO, you do gotta have good starting hands based on position and situation, and you do have to make sure you're aggro and not passivo... With good PFRing and good Aggro factor on flop turn and river...
Making sure you can fold a good hand isn't always good. I mean if you're consciously thinking you gotta start folding good hands, then you'll start losing money (or winning less).
Basically do what you can to make sure you aren't calling too much or too little. For me, in limit, I rarely fold good hands to 1 or 2 bets, unless it's 3bet to me or something like that, or the pot is smallish.
In NL my went to showdown stats were like 20 percent or something, maybe a little less. like 18. My WTS for limit is 33. Probably a little high, I'd like to trim it to 30, but as long as it's not ridiculously low or ridiculously high, I think I'll be ok. Same with you
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Cheers,
Gutzz