Yep, Gateway Server updates the gateway statistics every 4 to 6 minutes (random to distribute load). The RX and TX rates indicate the packets per hour. This is only indicative for the busyness and liveness of gateways. Although you can, I would discourage polling these values and converting them back to actual numbers (based on consecutive updatedAt timestamps), because you’ll be missing updates and with many gateways you’ll be hitting the API rate limiter.
We are working on a separate API for routing statistics, including per-gateway aggregates over time.