Where to put non-Dynamics objects?

We have custom apps/services/reports that query and update our Dynamics AX db.  Most of the objects (views, procs, functions) reside in a neighboring user database on the same instance, thus all the queries are built using 3 part name.  ie

select * from MicrosoftDynamicsAX.dbo.PROJTABLE

I have seen other posts where their goal was to remove all non-dynamics objects from the Dynamics db and into another user database.  Is this standard/best practice?  Should we continue to avoid putting objects not shipped with Dynamics into the Dynamics DB?