Some quite knowledgeable people in the field of BSD networking, including Henning Brauer, maintainer of OpenBSD's PF, have little love for instruction given on site you are linking to:
Taking settings for FreeBSD and blindly applying them to OpenBSD isn't a great idea, yeah.
Running the defaults is a good place to start, but if you don't get the results you're seeking, the linked articles show a lot of settings that are worth looking at.
There are a lot of settings that are reasonable to tune for specific uses, which is why they're configurable. Knowing which ones to poke at first is a good thing.
https://marc.info/?l=openbsd-misc&m=130105013025396&w=2