That's the goal, at least unless/until Nostr incorporates some form of aggregation for this info. Besides, for things like Likes, querying one relay isn't enough since people write to different relay sets. I'm aggregating data from all the top relays (currently 27 of them) so the reaction counts and follower counts etc should be pretty accurate. Nostrum is running on a high end production web server tied to a high end production database server, so it can handle quite a bit of load.