I have a book from around 1920 from the east parts of then Polish territory, where flour for the bread is measured in buckets, amongst others.
I guess it's down to a common understanding between the author and the reader, but I couldn't find an information on the bucket volume in there.

What my wife suggested to me once is that if you make the same recipe over and over, you could spend let's say 30 minutes measuring all the ingredients and putting them into seal top bags and then just taking a bag when you plan to bake. It could be a huge time saver.