Mid chest exercises

Press or fly?

These are two different jobs, not two versions of the same one. In a press the elbow bends, so the triceps and front delt come along for the ride - the weight is the heaviest and progress is the easiest to write down as a number. In a fly the elbow stays slightly bent the whole way, the chest works almost on its own, the load is necessarily much lighter, and the hardest point is where your arms are spread widest.

It is worth knowing where each version of the fly loses tension. With dumbbells on a bench the bottom is the hard part, and at the very top the weight stacks vertically over the joint and practically stops loading anything - hence the note in the description about not clanking the dumbbells together over your chest. Cables and bands behave differently, because the direction of the resistance does not swing around with your arms and the tension stays through the finish too.

Because they do different things, you rarely pick between them. More often one pressing exercise is the backbone and flyes come in on top of it.

Are push-ups enough?

Push-ups are the biggest group in this section and a chest exercise in their own right, not a lesser version of the bench press. There is one limitation and it is about load: your bodyweight is what it is, so you cannot add the smallest plate to it once a set stops being tiring.

The atlas works around that with variations that change leverage or range instead of weight. Deep push-ups with your hands on dumbbells let your chest travel below the line of your hands. Archer push-ups shift most of the load onto one side. There are also banded versions and versions where the weight is loaded on with help. That is why the push-up list runs so long - progress here is made of variations, not of added weight.

If you have a bench and a barbell, pressing does the same job with a number you can track from week to week. Push-ups do not stop working then - they just stop being the only tool.