I usually keep it separate, but I haven't heard of anyone running into problems in a few years, not since schema became more popular and dupes on google became less of an issue. Since you only have 3 locations, as long as you set it up right it'll probably be fine.
What I would do though: for any location specific pages, only have NAP and schema for the one listing. The only pages I'd consider having all of them, would be pages that are about the brand itself (home page, contact page, etc).
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