If your OpenBSD system is the final destination of your users' connections, then:
Packets from your users to OpenBSD cannot be managed by queues. Packets to your users can be queued.
Example: Your user sends you a large file.Each 1500-byte packet must be dealt with on arrival. Your system's short ack packets may be queued for their return to the user.
If your OpenBSD system is routing packets to another subnet -- commonly between your Internet connection and your LAN, then:
Traffic may be shaped as it passes through your OpenBSD system in either direction.
Example: Your externally connected user sends a large file to another computer on your local network.Each 1500-byte packets destined to your local network may be queued as they are scheduled for your LAN. The short ack packets may be queued on their return to your user.