As the old saying states, “boards don’t fight back.” You can take the time and effort required to punch through a board and you can throw your entire body into the technique since the board will not be avoiding, blocking, or counterattacking. If the break fails, you have time to regroup and prepare yourself for the next attempt. When the target fights back, such as when striking a human opponent, if you use the same striking technique you use to break boards when you attack the opponent, if the first attack fails, you will leave yourself vulnerable to counterattacks and may never get a opportunity to attack again.
If your watch boxing, you hear the commentators talking about how a fighter is losing the fight because he keeps “going for the knockout.” The fighter is concentrating on making powerful, follow-through, mass-committing punches, which take too much time and energy, usually miss the target, and leave the fighter vulnerable; while the opponent is using short, quick, snappy punches that hit their targets and cause pain and cumulative injury,
which usually leads to the fighter winning the fight.
Take the example of a side kick to the opponent’s midsection. If you try to kick through the person, there will be an initial impact force that does some damage, but any additional force is used to merely push the person backward, which causes little to no additional damage. If the kick is a snap kick that penetrates only a few inches, delivers its initial massive force, and then retracts before it has an opportunity to absorb the rebounding force from the target, then the target will receive the maximum force of kick, you will conserve energy, you will be able to regain your guard position quickly in case the kick misses it target and you are counterattacked, and you will be able to attack quickly again.