brisbane agm, page-11

NeilN,
It came from the presentation, refer to the one posted for the AGM,
under "Technology Acquisition" page 17, that the model assumes all of the above listed streams are resolved for it to work,
which includes multi fracture stimulation, and this requires multi fracture drilling, so it seems to me that multiple fractures are necessary.

You are right in as much as successful flow through one fracture from H1 to H3 satisfies a proof of concept.
And they are targeting deeper hotter rocks and a greater separation to achieve a greater heat transfer, but it appears a single fracture may not provide sufficient flow to give the required energy yield, hence their need to develop multiple fractures.
Up until now I had always though that 1 fracture horizon at the greater depth and with the greater separation with a nine hole array was sufficient.