As simple as this seems, it happens all the time even to professional fighters. Ronda Rousey is the classic example in her first MMA defeat against Holly Holm, she continually tried to press forward with punches only to be brutally counter punched by the taller and better-timed Holm. Despite being bloodied and battered over and over, she made no attempt to change her strategy. She didn’t pay any attention to what was working and what wasn’t.
f an opponent is consistently scoring against you, you must change your strategy. Countless times I have seen a fighter fail to defend a certain technique or combination but then fail to change their defensive strategy, and they end up getting hit over and over by the same thing. The definition of insanity is doing the same thing over and over and expecting different results.