A few companies in China compete over building construction times. Examples include a 57 story tower built in 19 days and a 15 story hotel in 48 hours. These are just assembled from pre-fab components, so it might be 3 years of prep followed by a few days of assembly. I think the end goal is prestige.

I'm partial to LiftBuild's method of building the central tower first, and then constructing each floor at ground level and hoisting it up the tower and into place. The bulk of construction is done on the ground, faster building with less rigging and safety requirements. I think they averaged 10 days per floor on their last build.

https://www.liftbuild.com/

The Empire State Building was a legendarily fast build, I don't think being slower than it means this is bad. For example, the One World Trade Center took 4 weeks per floor.

It looks like the glass is fully accessible: https://upload.wikimedia.org/wikipedia/commons/1/14/CBR_Buil...

The sentence you quoted continues:

> protecting the floors from the elements and allowing work to progress on the interior as floors above were still under construction.

so it seems the main benefit was that the construction could be pipelined better as the already in place glass helped shelter the interior.