Sanding grit levels can vary depending on the wood types and the finish to be applied. It can also depend on the state of the body and neck you get in the kit. A lot of the PBG videos were done a relatively long time ago, and experience has shown that in some instances there are improvements to be made on the advice given. Any videos too far from the norm have been removed but unfortunately have yet to be re-filmed (obviously this takes quite a long time to do over a build).
Some stains take better than others, so some need a rougher finish to allow the wood to absorb the stain than others, which will work on a smoother finish. It's never a good idea to go too smooth on the bare wood, as in most instances, you'll be getting the really smooth finish by sanding down the clear-coats to flat on the final finish layer.
Also, if you've been watching YouTube videos of North American builds or luthiers, then beware that there are big differences in US ANSI.CAMI and FEPA/Euro (as you'd normally find in Australia or Europe) grit sizes once you get above 220 grit. Micro-Mesh grits are also a completely different system. Many comparison tables out on the web, but here's the one I use: https://www.thesandpaperman.com.au/a...ion-chart.html
If in doubt, just ask, as you'll get the info given on what has and hasn't worked on that particular wood type with that choice of finish. You'll still get some variation, but that's life.