Oh really? I never understood burn-in; how does it work? And what do they sound like after burn-in?
It's a bit of a contentious topic. Supposedly the drivers will fully settle into place after some usage and because of that, there will be some audible changes as they settle. There's also some discussion with cables and dacs/amps that they need burn in too.
It's contentious because there is not a lot of objective evidence (or none really) to show any differences. Somehow also nothing ever seems to get worse after burnin, it's always mentioned positively, which also shouldn't be true. There's also a question that if things are better after burn in, why don't manufacturers just do it before selling them?
And there's a very real subjective phenomenon that we call brain burn-in where you just adjust to things you listen to a lot, to the point that they start to just sound "correct", even if no actual change has happened.
So, some swear by burn in, others, like me, think it's much more likely brain burn in.
So, you can do a dedicated burn in session as was described, or just use them normally. I personally just listen. If my headphones truly do change, I can enjoy the journey as I use them, and if they don't, then nothing gained or lost.
Also for the atlas, my experience was that after I adjusted to the sound, the bass felt much more balanced with the rest of the sound whereas originally they sounded very bass heavy.