The argument against practicing Rock Paper Scissors sounds reasonable: if the theoretically optimal play is pure randomness, what are you practicing? You're not trying to get better at being random. You already know how to flip a coin.
The problem is that "just be random" is advice that almost nobody can execute reliably. The research on this is clear. Ask someone to produce a random sequence of throws and they'll produce a sequence with structure they're not aware of — avoiding long runs, clustering certain throws, cycling predictably after losses. These patterns aren't random. They're exploitable. And the players who know about them and who have done the work to interrupt their own behavioral defaults have a genuine competitive edge over those who haven't.
That's what practice in RPS actually looks like. Not drilling hand gestures. Monitoring your own throw distribution. If you throw fifty consecutive rounds against a practice partner and track the results, you'll find your distribution is almost certainly not equal thirds. One throw appears more often than it should. Another is underrepresented. That skew is a tell. An opponent who figures it out before you do has a real edge.
The second area worth practicing is timing. Clean, consistent reveals on the count are the physical foundation of fair play and they also minimize one class of physical tells. A player whose hand commits early during the priming phase is broadcasting their throw to anyone watching closely. Drilling consistent timing — committing only on "Shoot," showing the full gesture cleanly, not rushing or stalling — removes that information from your opponent's read.
The third area is opponent reading. The win-stay/lose-shift pattern shows up enough across enough players that it's worth having a habit of noting it during a match. Winners repeat, losers cycle. Not always. Not predictably enough to bet your life on. But predictably enough to inform the next throw.
None of this takes years. Tracking fifty throws to find your distribution takes one practice session. Working on timing takes a few more. The return on that small investment is meaningful in a tournament context. Whether casual games justify the preparation is a question of how much you care. The answer to "should I practice" is yes, but the thing you're practicing isn't the throw. It's yourself.