I actually just cleanse the whole room, usually using smudging, as and when it needs it, and I have wards set up for the whole house, property and “craft room”, as I call it (see what I did there? 
), that are meant to permanently keep out uninvited energy.
The intention is, that while it’s not 100 percent fix and forget, I want to be specific and notice unwanted presences and deal with them specifically, not generally. I have not had issues with “randoms” since I got my warding techniques sorted a few years ago.
I posted how I smudge here:
More about wards:
My craft room is a dedicated space through, that is only used for magick, and has ongoing projects and open sigils and whatnot that I don’t necessarily want cleared out willy nilly. If this isn’t an issue, or you’re using a living space, then banishing the whole space is what I would do. My circle is an enchanted circle I painted on a bedsheet with acrylics that is a personalized fusion of a few ideas: it draws attention to me, enhances my evocations, and holds elemental balance.
For using the room for a new ritual in circle, while there’s all that energetic activity still happening on the altar and in various places around the room then, what I do is open the circle energetically. I do not banish, I rely on the boundary created by my opening of the circle to move me into a liminal space that is separate from the room an regular reality. Nothing can come into this circle that I do not invite because this is my own little world now.
I have two ways to open a circle depending on what I want. I used to go to drumming circles with a Peruvian Shaman, and to this day I use their technique for opening a safe circle, which is to call in the six directions (4 compass points plus Sky and Earth). Or, I stand the circle to open it, visualising the outside line glowing and just declare it open.