Yes, that is the standard way of making archive volumes. "Standard" as in not just recognized as good practice, but also the default way almost all programs do this.I was a fan of the "parts" system. where it was say part 1 through 5. You extract one and they ALL extract where they need to go. And lets be honest, there are games bigger than this with one file. I have a cable connection. It's ok, I can download all at once.
There does sometimes exist a reason one wouldn't want to do this, and instead separate specific chunks out each into their own compressed folder, but I'm unsure if there's a real reason it's being done so here.
Either way, it takes the same amount of time to extract. All it does different for the end user is save a few mouse clicks when done as volumes instead of individual archives.