Late but hope this helps! Yes, you select one of the outfits on the permanent banner to focus and every 5star item is guaranteed to be a piece of that specific outfit, and you won't ever get a duplicate of any of the pieces so completing the set is easier. As for the limited banners, you have the option to choose a specific piece from the current outfit to prioritize! Also, so far Crystal Poems is the first and only 5star ability outfit that is meant as an alternative to the default 4star Wind of Purity because both have the purification ability ^^
Late but hope this helps! Yes, you select one of the outfits on the permanent banner to focus and every 5star item is guaranteed to be a piece of that specific outfit, and you won't ever get a duplicate of any of the pieces so completing the set is easier. As for the limited banners, you have the option to choose a specific piece from the current outfit to prioritize! Also, so far Crystal Poems is the first and only 5star ability outfit that is meant as an alternative to the default 4star Wind of Purity because both have the purification ability ^^