Poker strategy has gone through so many changes over the years. Play tight aggressive, play loose aggressive, only 3Bet with the nuts, 3Bet with a 10% range, don't be a donkey and call down light, be a donkey and call down the aggressive regs light, polarize your range, merge your range and on and on and on.
And then we have the endless math theories, coaches and training sites, software tools, "solvers" and everything in between. Honestly, it is enough to make your head spin.