I like metaphors. I often think in metaphors. They are useful to explain thoughts or ideas (if speaking with someone intelligent enough to understand). They can add color to descriptions in a novel.
Here's one I thought of recently, but can think of no place to use it in a novel. (That's another purpose for a blog: a place to dump worthless metaphors!)
The name he'd been struggling to recall for weeks popped into
his head, like an air bubble rising to the surface of a swamp
from a corpse anchored to the bottom.
And, speaking of air...
Did you know that you can't put air--the same or different--back into a burst balloon?
Okay, that's not a metaphor. But, given time, I could come up with one.