Re: Poor instructions
1930s USA autochangers could flip a stack of 78s. So a symphony on 6 x 78s was as you describe, parts 1 to 6, then 7 to 12 just by flipping the stack.
They had sapphire stylus too, as the steel needles are only single play!
1949 was the first year of microgroove 33 & 45 with 78 and a flip over stylus. The current retro style record players have a 78 speed, but can't play a 78 disc properly as they only have a single stylus of microgroove type.
There were 12" 33 in early 1930s but 78rpm, for cinema, playing from inside to the outer edge like CDs / DVDs do. Easier to cue.