Yes, your extra steps are necessary to get the document to use a facing pages master. In fact, quite a neat way of achieving that end. You could, of course, just make a new master spread and then apply that, but you'd have to manually edit the masters to get them the way you want them. On the other hand, assuming you want to have asymmetry on your left and right pages, you will now need to edit the master you created anyway -- be sure to switch on Layer Adjustment before doing that.
And, if you're in a situation where you have a lot of master pages, then you have more work to do.
Converting a document to facing pages does not, in and of itself, convert existing single-page masters to facing page masters.
Dave