One of the most important components of an absorbing book, I think, is the pacing. There needs to be a balance of faster or more upbeat sections and slower or more relaxed ones, and ideally they should be evenly distributed throughout the story. The slow spots provide depth to the story (and allow the reader to metaphorically catch their breath), while the fast ones drive the plot forward. Too many slow scenes and the story drags, too many fast ones and it feels shallow and leaves the reader mentally winded.
It’s kind of a tough art, but there are lots of tools out there to help you if you find you struggle with pacing. One of the ones I most frequently see referenced or shared is the "beat sheet" from Blake Snyder’s writing-help book Save The Cat. This blog post by Jami Gold has a helpful discussion on it. Although the book (and his use of the beat sheet) is intended for screenwriters, it’s also very useful for novel-writers. Liz at Liz Writes Books has adapted Snyder’s sheet and created an Excel version of it for novelists, which you can download from this page (she also has a short discussion about it at that link, too).
I’ve been lucky in that pacing seems to be something I’m reasonably good at (I just have my weaknesses in other areas, instead ;) ). For me it ends up being a partly subconscious thing, a gut feeling about whether the next scene needs to be fast or slow as I’m drafting. I don’t usually think about whether I’ve had too many fast or slow scenes in a row, or where I am in the manuscript.
Interestingly, though, I was thinking back over my completed manuscripts and the pacing seems to follow roughly the same predictable pattern in each:
Around 4000 words (usually end of first chapter) – Inciting incident that triggers or introduces the main story conflict.
Around 15000 words (roughly fifth-way point) – Minor action/tension scene.
Third-way point – First major action/tension scene.
Halfway point – Big emotional action/tension scene, usually the turning point of the MC’s character arc. Biggest non-climax scene.
Two-thirds point – Second (and last non-climactic) major action/tension scene.
Three-quarters point – Trigger incident that starts ball rolling toward climax.
Seven-eights point – Climax.
And then the denouement, obviously.
And in between all these fast scenes I spread out the slower scenes (many of which may also have action and/or tension, but not to the degree that these point scenes do).
My current WIP, Stars, is being written with a dual POV, which is the first time I’ve done that. And it’s really messing with my sense of pacing. I think I’m still managing alright, but I guess we’ll see when I finally send it off to my CPs in a couple months.