Anthony Frost wrote:

There's also a considerable difference between feeding 30 engines from
a single set of tanks and feeding each group of nine engines from its
own set of tanks. The more complex the plumbing, the more potential
problems there are.

N-1 plumbing was a complex and heavy mess with so many long pipes being
involved that it was almost begging for some pipe or weld seam to fail
under launch vibration.

Pat