I am new to boxing and my instructor tells me to keep my hands high near my cheekbones at all times, but I've noticed that many boxers keep them lower. Is this just something that all newbies must do?
There's keeping your hands up high, and then there's covering up completely. Usually the one leads to the other.
A high guard allows you to transition to a cover-up real quickly. It also keeps your opponent completely visible. And it lets you punch.
Covering up is where you put your hands on top of your head or just in front of your head, completely covering your face with your arms, elbows close together. Covering up is 100% defensive. It just protects your head. You won't be able to punch at all. And it makes you vulnerable to punches to your body, so you often see people bending forward to move their torso back away from their opponent when they do this. It can really obstruct your vision, so you might find it hard to see what's going on.
As a novice boxer, these two positions are going to be your bread and butter. You don't have much else in your arsenal, yet. So you'll need a strong defense. And the high guard to cover-up gives you that. You can return to the high guard after you've gotten away from your opponent enough that you don't need to cover up anymore.
Why not block instead of covering up? The answer is that actively blocking a punch takes time. By the time you see a punch coming, it's already too late to block. The only time you have left is to quickly raise your hands from the high guard position to the cover position. You'll figure this out soon enough through sparring.
Here's what tends to happen with people who have absolutely no training in boxing when they go to spar a boxer for the first time. If they have some martial arts training (karate, TKD, etc.), they might begin with a large stance and their arms extended outwards pretty far. And they might be able block a punch or two, at first. Then what happens is they just keep getting hit in the head over and over again. After the first 5 times they get hit in the head, they decide to just cover up their head.
People will ultimately end up covering up just like boxing teaches. It's interesting that people find this out all on their own without any instruction whatsoever.
So that's the first realization. Without training and experience in boxing, your best bet is to protect your head and try to move a lot. Otherwise you will get pummeled, and you're not going to like it. Therefore, this must be the first thing you learn how to do in boxing. It is the most fundamental technique to learn in the beginning.
Later on, you'll get more training and experience. Gradually you'll have more in your arsenal. You'll be able to read your opponent better and to know when you're safe. You won't need to keep your hands so glued high near your head. But at first, it's going to be necessary.
And by the way, even the best boxers sometimes / often have to cover-up. You see it a lot in professional boxing. It happens when they're getting pummeled, and they don't have the ability to move out of the way and counter-strike. It happens when boxers are hurt or are just out of energy and need to relax and let their opponent use their energy. And it happens when boxers need to get in close to their opponent. These are times when they need a shield around their head.
You may not see others in your gym doing the high guard or the cover-up very often. There are reasons for that. First, they may only have to use it very quickly before transitioning to something else. It's easy to miss. Second, they only need to do it if they're worried about keeping their head defended. That usually only happens if they're facing an opponent who has much more skill or if they're in a heavy hitting match, both of which typically don't happen in sparring sessions. Third, in sparring they're attempting to practice new ideas and new strategies. Sticking with the high guard doesn't let them do that.
Hope that helps.
Yes. When you start out, you haven't built up the right reflexes yet, so it's better to have your hands protecting your face. More advanced boxers adopt a lower placement because they're confident in their ability to raise them quickly, and lower portion grants better visibility and ability to protect against body blows. Since brains don't heal, it's best to start out focusing on protecting your head. As you get better, you'll be able to lower your hands more.