Yep its a old trick back door stuff away from prying Eyes
Work with an Old school Yorkshire,Man. Ledgers,, (Logs) Transoms,, (Loggers)
Now you know the way it was when they used wood
Its a classic
I am not defending this and have not done the calcs on it but the board on edge has a structural capacity so in principle this could work and in calculation may work.
(Would not however recommend it!)
Alan you are correct and this was common practice many years ago , but only ever seen in domestic scaffolds where there is little or none policing of industries regs , but it works
I can remember designing dance floors made using splitheads or Acrow Treslegs with boards on edge supporting the deck - nothing wrong with that.
I don't think that I would cantilever boards off clips though!