Reply To: Apply style to every other/every third paragraph?

Instead of paragraph breaks use line breaks ( shift+ enter), create bold character style, in nested style dialog box choose you character style and through 1 forced line break, then apply two empty {None} styles and then again your bold style with through 1 forced line break, then one more style and choose {repeat} last 3 styles. Maybe there's better way but try this, it should work just fine