PraziPro Safeguard for Guppies
 

Is it standard practice to medicate guppies "every month or so with Praziquantel powder or PraziPro" as to ward off worms or other?

No.You should only medicate as needed and only when you're sure what you're treating. Most meds are hard on fish. I would assume worms or other parasites will only show up in your tank when you physically introduce them into your tank (with new fish, snails or plants).