My Plot and Structure book recommends you detail your plot on index cards, then shuffle the cards. Supposedly it makes you weave more surprises into your plot.
I have inadvertently done this by chopping up my first half. Since I sent the oilman husband off one month early, this has happened:
His mental illness is more ambiguous, which better serves the plot. Well, in the first half. I haven’t made it to the second half. It could be utterly trashed.
There’s a lot more tension. You know she’s screwed, but she’s oblivious. Plus, her march toward disaster is a bit more her fault. It’s more interesting.
You don’t get to know him as well, so you are as unaware as the heroine is as to why he left.
It’s a longer gap between when he leaves and when [Spoilers!] he returns, maybe long enough you are surprised.
Hah. Maybe he never returns. Maybe that would be better. I could do anything.