The issue is a bit more complex: When you asked me, I usually answer sincerely which means there's at least a few chunks of info the following conversation could build upon. That's the flow that feels more natural to me. Adding a "How about you?" at the end feels like shoehorning a formality in there and interrupting the "natural" flow. It also makes me feel kind of dishonest to add it anyway even though I feel like it's not fitting.

I avoid this whole issue by trying to ask first and ask follow up questions before they can add pleasantries.