Here are some of the best squat variations in existence. Adding one or more to your training plan will go a long way in preventing accommodation and overtraining.
These variations will of course differ in terms of how well you respond to them, how long you respond to them, and how user-friendly they'll be based on your anthropometrics. Since there's no such thing as a one-size fits all approach to training, you'll have no choice but to experiment.
The stimulation you get from a Zercher squat is quite different than what you get from a front squat. In fact, your front squat numbers may not correlate at all with your Zercher squat. (I can actually Zercher squat 50 pounds more than I can front squat.)
The disadvantageous joint angle achieved by the bar-cradled-in-arms Zercher position forces you to engage the anterior core and upper-back. Couple that with the dead-stop off of pins (the "Anderson" part of the movement) and you've got one brutal, quad-bruising movement.
Oh, and don't pay attention to the keyboard warriors who call Zercher squats dangerous. They're about as wrong as they can be.
The popularization of the box squat is largely due to Westside Barbell and Louie Simmons, and doing them with a wide stance has definitely been a game-changer for every athlete I've used them with.
There are a couple of reasons they're so great. For one, the wide-stance box squat breaks up the phases of the lift because you sit back on the box on each repetition, forcing you to use less weight (which means less spinal compression) while preventing you from using the stretch reflex to get out of the hole.
Secondly, the wide stance puts a great deal of stress on three areas where most lifters are lacking: the hips, hamstrings, and adductors. It's also quite forgiving on the knees since there's less shear force. Overall, the wide-stance box squat is arguably the biggest bang-for-your-buck squat.
If you need proof that paused squats are effective for developing absolute strength, watch Dimitri Klokov perform them with an ungodly amount of weight.
The great thing about them is that you can vary the length, location, and number of pauses, and whether to do them during the concentric (lifting) or eccentric (lowering) part of the movement. Paused squats will help reinforce good positioning as well as provide additional time under tension – a win-win.
If you increase time-under-tension, you can effectively increase the length of your sets, inducing additional muscular hypertrophy. Adding a one-fourth rep to each full rep will increase the length of each set, as well as reinforce proper positioning with your squat pattern.
Assuming your goal is hypertrophy, do these at the end of your leg workout for sets that last somewhere around 30-40 seconds.