In writing, varying the lengths of paragraphs is important. Dialogue is one way to alter the pace.
I frequently see sample pages that replace dialogue with verbal asides, thinking this is an acceptable substitute.
The author feels the need to let us in on the character’s thoughts but doesn’t want to say them outright. Either they think in-head POV is cheap storytelling, or there’s a lot of thinking in the scene already and they recognize any more would detract from the action.
So instead, the character talks aloud.
“Did something just move in those bushes?” she mused. “Nope, gone too fast. It’s not her.”
It comes off as annoyingly as Megan in Young Justice, who berates herself by name every five minutes.
Unless your protagonist talks to herself for a plot-related reason, like a behavioral tic from her time with the aliens, leave it out. Either trust the reader to pick things up from context (suspense should be implied, not told), or give the information from inside the character’s head:
The twilight deepened. Something seemed to move on her right, but it was gone too fast to be her opponent.