There are tons of ways to break down The Claremont Run, being that it encompasses 16 years and many many changes to the makeup and ckncept of X-Men

I like to think there are three majof chunks marked by soft reboots

First is The Phoenix Years, from Giant-Size X-Men #1 to Uncanny #176, marked by the interstellar AND psychological drama created by Jean's transformation into Phoenix, largely seen through the eye of Cyclops

It ends with the "happy ending" for him and Maddie and gives way to the Lifedeath Years. The main villain is the Government. "Days of Future Past" is constantly invoked through Rachel, Nimrod, and other gov initiatives (Storm's depowering.)

That's more about the environment of the stories because they also spend a LOT of it on mystical mumbo jumbo like Selene, Kulan Gath, the Dire Wraiths and the Adversary.

Emotions become more raw and severe, characters more hard-edged. I call this era "paranoid and pointy."

I say it comes to an end with the Fall of the Mutants and gives way to the Blockbuster Era. More and more giant crossovers of extended length and outsized stakes. Superstar artists. You can feel the franchise slipping away from CC years before it actually does.

Take Inferno, which only exists because of something someone else did to Jean Grey, and the way it impacted what Chris wrote for Maddie. Or the drawing together of the new teams because editorial and the market demand it!

Anyway, that's me wearing my @ClaremontRun hat. Take it for what you will!