In Hermetic labwork, there is always a single individual acting as head researcher, and ordinarily he's the only one who gets the spell at the end. But Solomonic groups (TC&TC 38) don't have a single leader - they have the guy who summons the spirit (normally the guy with the highest Solomonic art - I note that this is not always the best strategy, whatever the book says), the project manager (not always the same person), and everyone else.
So the question is, who gets whatever spell they were inventing? Is it only the guy summoning the spirit (that's how it works with Hermetic magic, but the text here doesn't seem to imply it), any one chosen member of the group, or the entire group involved in the project (that's what I'd take away from the text, and to an extent from the advancement rules, but ay yi yi that makes knowledge propagation simple)?