so we design these lengthy websites, but have you ever fully read a website?

Depends, if it's a content site like a blog or article then I'll try to read as much of it as I can, but most of the time I'll just skim through, search for the keywords I'm looking for and if I'm interested, click on the CTA button

Even with content, if it's boring or if I don't care much about it, I'll skim through and pick out the general points and move on. How easy you make skimming through your site and getting all the information I need determines how much I like it

Yes, I was thinking of marketing, software/service kinda websites. We spend so much time articulating, animating, designing, and working on the thing. But then it struck me, I never go through a website—usually just signing up if the hero tells me enough.

How I like to think about is that you're designing a movie when the user only needs a trailer. The trouble is that multiple types users need different kind of trailers, so you stitch these trailers into a movie that's too extra for any one kind of user.

I like this @skepticacid