TDI Flywheel 1Z: Solid for Longitudinal Engine Install

I was randomly browsing on the internet the other day, and I noticed something:

Audi used the same flywheel in all of its 4-cylinder engines starting in 1987.

026105269L Flywheel
It doesn't matter whether it's a gasoline engine, a 1.6 TDI, or a 1.9 TDI.

Clutch kits are available in two sizes: 210 mm (for most models) and 228 mm (for TDI models and high-performance gasoline engines). However, both sizes are always used with the aforementioned flywheel. The friction surface on the flywheel is perfectly flat, which means that the clutch pressure plate determines the maximum size of the friction disc.
According to my uncle, the flywheel was also used in 4-cylinder industrial engines, and apparently still is to this day.

What do theoretical practitioners say about the always identical moment of inertia, regardless of the engine?

When Volkswagen installed the transversely mounted engine, they took a completely different approach. The 1Z flywheel has significantly more mass than the one from the old 1.6 TD engine. Why wasn't this necessary with a longitudinally mounted engine?

Regards,
Jens.