I got to know him much better through these productive interactions then awkward smalltalk in a 1:1.
And it kind of make sense to meet privately quarterly since perf reviews are also quarterly and that's the only reason I can really think of for a private scheduled face-to-face.
Of course I could always just ask for a private meeting anytime I wanted, which I guess I did from time to time. But it always for a product reason: a tough tech choice I was wrestling with or similar.