I used to put all my Scots language poems in the 'Burns Night' collection, even those that had nothing to do with Burns (other than the language used), but the Scots language is so much bigger than just Burns, so I decided to separate out the non-Burns stuff into it's own collection.
I mostly use Scots for humourous poetry, but hopefully I could see it being used for some political pieces in future as well, or affectionate addresses to children and animals.