Yes and No. But also trying to keep things simple and within the scope of easy GUI methods.
Balance is a bit of questionable item when running on single disk. Everyone runs out of disk space at some point > Error No Space (enospc)
Yes, possibly in hind-sight, the article should have expanded a little more on this. Possibly.
The Btrfs docs state on line one that the “primary purpose of the balance feature is to spread block groups across all devices”
They also go on to say that the process can be very intensive and, somewhat ironically, won’t run if there isn’t enough space there to start with.
What they don’t say, at least directly, is that running a balance occasionally may help with adjusting the way that space reported. That’s discussed on a separate a troubleshooting page.
Heavy deletions of files and snapshots can cause the Data reporting to go slightly out of sync with the Meta-Data logs.
The BTRFS-ASSISTANT wiki gives no discussion on the matter, in the same way that it also omits suggestions on snapper numbers.
However, following on from your comment, I did do some looking at the btrfsmaintenance code that installs along with the assistant. These are quite surprisingly old SUSE scripts that have been packaged together. The btfrs balance commands are up-to-date but I am not sure that all the script calls are linking up properly on their journey from the assistant.
If you run the btrfs-assistant balance command from the front menu panel it seems to by-pass the SUSE config script that adds filters to reduce the running intensities.
What I would currently recommend is to run the balance command at the terminal. Adding =50 filters will speed things up considerably.
Try sudo btrfs balance start -dusage=50 -musage=50 -v /
with sudo btrfs fi usage -b /
before and after to see the difference.