Well it's hard to say with the slow release MG... Some strains use more nutes than others. If the plants look healthy then just keep doing what you're doing. There are some threads around with pics for diagnosing plant problems (I think there's one in the first link in my sig), familiarize yourself with the deficiencies so you can spot them if they show up.

Does the PK bottle have instructions? Normally I'd say follow that, but my PK bottle's instructions screwed up my plants, or so I believe. It said to apply every watering. Problems went away when I backed off and used occasionally based on the Canna feeding schedule.