If you are talking about a bearing assembly that the races and bearings are one unit that stay together, then yes I'd think that should be drop in. But wouldn't be bothered if I had to push it in with a firm force or maybe even a light tap with a mallet. A little bit of grime or something could make it not be as easy as drop in.

While you said all the proper stuff, it did get a little confusing to me seeing headset, bearing, race all in a short and brief sentence or two. Plus, I never assume I'm conversing with someone that actually knows what they are talking about. Apparently you do!