[JulianK]

Just for another perspective, my experience doesn't really align with this. From my (biased) perspective, this sounds like "in theory" as opposed to "in practice" so I'm honestly curious if you've managed to get away from having to really deal with cross-platform differences.

I know that in theory you use a cross platform engine that hides away all the messy details from you.In practice, I've found the PS3/360 have quite different CPU/memory architectures and you start dealing with the reality of that sooner than you'd expect. Whether that requires manually down sizing certain swaths of textures or writing code that will run on the SPU, there's quite a bit of manual work involved.

Also, most game studios tend to roll their own tech which generally requires at least a small cadre of people manually targeting and optimization for each platform.