A few honest signals: you're managing cash across three or more bank accounts or entities, someone spends real time each week manually reconciling balances between them, you're holding meaningful reserves that could be earning more, or you need payment approval controls beyond a single shared login. If none of those apply yet, a treasury system is more complexity than the problem calls for.
Want the full method? See what is a treasury management system, and do you need one yet for the full breakdown.