Yeah, the packets were complete vertical slices of the game, instead of just a few classes or whatever at a time. Classes and features would often change significantly from packet to packet (though that settled down in the later packets as the design started to solidify). And, we were testing player-facing and DM-facing mechanics simultaneously throughout, and there were a couple of modules provided with which to test the material. Definitely felt more like a real playtest, rather than just sort of a vibe check, IMO.