Short answer: Roughly 2/3 of the time.
Long answer: It depends.
I find my style is fairly balanced when it comes to establishing shots, scenes that continue from locations set up in the establishing shots and close-ups. In establishing shots, my backgrounds are 'detailed' and usually take center stage. In the 'continuing' scenes, I usually just have impressions of backgrounds; like just a door and partial doorway if the characters are interacting with an already established door, or recently went through a door, or walking towards and then away from a door etc. In close-ups, I rarely have backgrounds.
Seeing as I'm balanced between those three types, that's where I came up with the roughly 2/3. Although, I have heard discussions where the background impressions in the continuing shots don't count as true-blue backgrounds. So, your mileage may vary.