Are there any real benefits to turning on wifi location scanning?
Solution 1:
Does anyone actually recommend using wifi scanning, and is it helpful for actually making sure you are in the location you are
Yes, particularly if you play in a dense urban environment where satellites may not have direct line of sight to your device. As you've clearly noticed, GPS alone can sometimes be very unreliable (sometimes to your benefit), and Wi-Fi positioning will often "take over" in these cases and make sure that your position is at least roughly where you actually are, rather than teleporting all over the place.
Additionally, Wi-Fi positioning being enabled will dramatically decrease the likelihood of the game ever coming up with the dreaded red "Location not found" banner if GPS is failing entirely. In situations like this the Wi-Fi positioning will not typically be enough to actually track your movement and you'll end up locked in place until you go somewhere with stronger GPS, but you'll at least be able to spin and catch whatever is around you in that area.
If you play exclusively in suburban or rural areas, it's unlikely to be of any benefit.
or is it not that useful and takes up battery?
Wi-Fi positioning uses a completely negligible amount of battery (especially on Android 11+ phones, which can use it even with normal Wi-Fi features disabled).
Would it also technically take up more data?
Yes, but again a completely negligible amount. Communicating access point metadata to a WPS location API would require only a few hundred bytes. Pokemon Go would use more data every minute than wireless positioning would over the course of an entire day.