The squeeze press is one of my favorite mind-muscle connection builders for the chest. If done properly, no other exercise will teach you how to recruit the pecs as quickly.
I like to use it early in a workout or as the first exercise in a superset, especially if you have trouble feeling your pecs working.
Because of its nature, you can actually do this exercise very frequently. Every day in fact. Why? Because it will cause next to no muscle damage, so it's super easy to recover from.
This is why it's my go-to exercise to fix a lagging chest. When you have a lagging muscle, most of the time it's simply because you're not good at recruiting it. And the key to becoming better at contracting a muscle is to practice it often. No movement will teach you how to flex your pecs better than the squeeze press.
If you're using it as a true hypertrophy tool, not for motor learning, you must go to the point where it hurts/burns. Do sets where you'll be under tension for at least 30 seconds, more likely 40-60 seconds.
Why? Because this exercise won't cause much muscle damage or mTOR activation, so you need an accumulation of local growth factors and lactate to grow. The higher your discomfort tolerance is on this movement, the more you'll benefit.
How to Do It
The squeeze press is a dumbbell bench press with one slight difference: the dumbbells are kept in contact with each other at all times and you're actively squeezing them inward (against each other) as hard as possible. This simple action will shift all the stress onto the pecs.
Squeeze as hard as possible during every inch of every single rep. This is what makes this exercise effective.
Use a slow concentric/lifting tempo. This makes it simpler to hold a maximum inward press. It will also increase the time under tension, allowing you to more easily reach the required lactate accumulation and local growth factors release.
If you execute the concentric portion in 3 seconds and the eccentric in 1 or 2 seconds (a rare occasion where the concentric should be slower than the eccentric) you'll need 8-12 reps to get into the right zone.