Many players complain about their breaks, but most of them are guilty of not practicing their break shot.
I hear "my break sucks" often. I ask, have you been at a table alone doing break shot practice lately? Usually the answer is never.
For a lot of people, their only break practice is the accumulation of all the breaks they've executed at the start of games.
The reason for this is because out of all the types of practice and drills, breaking is probably the most tedious. But that's no excuse. Have to get a table, rack the balls, and break. Take note of the results. Re-rack and break again. And again. A good session would be at least 20 breaks. It isn't uncommon to shoot a practice shot or drill shot 20 times before moving on to another drill or shot, why would it be different for the break?
In breaking, it is much better to start off slow than fast. People think break practice is all about blasting balls at max speed over and over until they get it right.
Starting off with lower speed is best because the lower the speed, the closer to your playing stroke you are, the more control you have - the more accuracy you'll get.
Breaking isn't only about speed, it's about accuracy. A guy who slams a ball at 25mph but clips the 1-ball will get the same or worse spread as the guy who hits the ball at 15mph, but gets a nice clean direct hit on the 1-ball.
As the saying goes, it isn't what you make, it's what you keep.
That applies to breaking. No sense in going full speed if it is uncontrolled because you wasted all that extra speed and energy by not hitting the rack square. Totally defeats all that extra energy put into the shot. You ever see some people hit medium power breaks yet get good spreads, make balls etcetera? That's because they hit the rack very accurately. They are more efficient. All the energy they put into the cue ball is going into the rack.
At max speed, it's more difficult for you to self-diagnose any problems. Much better to start off slower and work your way up in speed. As you do, you'll start to see what is uncomfortable, or what exactly is it that is causing the lack of control. You'll feel the boundary between control and out of control and will be able to then make corrections. At max speed, a lot can be very wrong and it's hard to tell what.
Obviously, making a ball on the break is important, but so to is cueball control. They are probably equally important. I see powerbreakers smash the crap out of their racks all the time, make balls, but end up with no shot whatsoever because the cueball is glued to head rail or foot rail. They just assume it was bad luck. That *can* be true IF the cueball was kicked there. But many times it has nothing to do with luck, but instead, lack of control. It never dawns on these players that their sledgehammer break that spread everything all over the place and made balls was completely and utterly a waste of their time and efforts because they didn't have a shot afterward.
I'm no instructor, nor expert. But I'd wager that it's better to develop a cueball control break first and then work the speed up than it is to start off fast and try and then learn how to control the cue ball. Better off with a weaker break that hits the balls square, leading to more efficiency and a decent spread and balls made as a result, while getting the cueball to stay in the middle of the table.
But this takes patience. It means the player is going to have to suffer through a period of time in their game where they aren't getting the results they want. Especially when they know they can hit the rack harder. A lot of players want to execute crushing breaks and that to them is success. Whatever happens, happens. Cueball, balls made, rack spread and all of that is all luck to them. They only hold themselves accountable to getting the big hit on the rack and the rest is up the pool gods. That's the wrong approach. They should instead measure the success of a good break as where the cueball ends up (prior to being kicked). If you plant it right in the middle of the table - consider that successful even if you didn't make a ball. The rest will fall into place as you increase speed.
For a while, my performance was going down. It was for a lot of reasons, but one that I overlooked was the break (8-ball). I had been slacking on break practice. I corrected that by breaking at least 20 times per practice session. Multiple sessions over time. Working on accuracy and cueball control, then ramping up the speed after the first two elements were becoming consistent.
Well, it really worked. Imagine that. Practice worked!

My matches all of a sudden started becoming much easier. It really helps quite a bit when the cue ball is in the middle of the table, offering me many times more options, I make 2-3 balls on the break, and there are less clusters or none at all. Sure sounds like DUH doesn't it? I said that to myself. Control of the table is great, I can run out or play to a safe. Less problems, more options. All of that makes the situation better for me. That's what happens when you slack off and just expect things to happen on their own. It's so very easy to become accustomed to dealing with what you've got on the table that you overlook the break. A great break literally allows you to play a completely different game. An easier one.
That said, it's one of the most worthwhile things to practice, even if it is tedious to rack balls over and over and break them.