Building up is important in any climatic story.

Everything that happens must build the tension, mystery or emotion to really create that big climax.

For example, if a character is becoming insane, show little by little how his mental stability slowly deterates. So that once your a few steps from Coo Koo land, your character can take that big step as the climax, showing the full change.

On the topic of insanity, it could start slowly with trances and staring blankly.

Then it can move to voices within the head, uncontrolled actions, thoughts, emotions, perphaps building up till he or she is unable to connect to the outside world and the climax takes place.

If a scene is to be sad, you must build up how and why this emotion is displayed, how it gradually increases, until the readers feel for your character, then the climax ends it with a bang.

You dont need to build it all up in one chapter. Distribute it evenly tjrougout the book. Unless the change is increasing quickly, keep them spaced out, so the reader can slowly see the changes.

For example:

Chap 1 - Rick is just sad from his brother's death.

Chap 3 - Rick starts to cry to himself when he sees other boys.

Chap 5 - Rick no longer hangs out with others

Chap 6 - Rick avoids people all together

Chap 8 - Rick starts to snap up at people who try to talk to him

Chap 11- Rick becomes aggressive

Enter climax

End? - Rick killed some people.

The emotion must be built so the readers can understand instead of wondering how did a sad crying boy turn into a vicious killer.

Not meaning they have to be named Rick, or that you need to do it in the same order of chapters, but you have to be able to convey the message clearly to your readers, "Rick is overcome with grief, its making him change."

If you have an exellent build up, but the jump between the tip and the climax is too small, people do not see the climax as a big burst and assume it is another build up, which will lead them to being disappointed.

The same for the tip and the climax jump being too far. The readers may be confused if you skip build up 8 and 9 and jump to 10. This will make the character or story seem unrealistic and people may think you are desperate.

Building up requires momentum, like walking, to running, to taking that big jump. Every piece needs to fall in step, no pun intended, and needs to fit in, to show perfectly what you want them to see or feel.

Slow steps, walk steps, run steps and jump.