Well, no, not "a" levels layer. As many levels layers as it takes. Some photos require as few as 5-10, others 20-30. But yes, in a general sense, your point is correct - you edit your photo to your satisfaction first.
May I see the SOOR of this photo? ("Straight out of Raw" - that is, the raw processing done, but no Photoshop work yet.) I need to see how the background was in the original photo.