It’s a habit I picked up in basic training. We had 50 girls to 12 shower heads, and we really didn’t get much time for all of us to shower at all in the first couple weeks (the time constraint was relaxed after a bit though)

The tooth brushing deal though I think was because our TI would find the tiniest speck of water in the sinks after lights out and absolutely lose his shit. So we only used the sinks to wash our hands, so we didn’t accidentally leave toothpaste in the bowl of the sink and miss it while cleaning up for the evening.

Either way, it’s just a habit that’s stuck with me through the years.