Yes. Yes. Yes. I used to have a 2.5 hour drive a few times a month when I was in college and would load up on caffeine and have pretend interviews or hot topic debates with myself in the car the whole time. I didn’t do it specifically to practice better fluency, I just liked the feeling of speaking fluently. It took some time, like a year or two of consistent practice, but I noticed a definite improvement in my speech. The same kind of thing happened after college too. I ended up with a job which requires me to talk a lot, and have noticed improvement there too. Practice makes perfect.