> I hate this requirement (and other similar ones). They force the crystallisation of architecture long before the concepts they model have them selves had time to fully crystallise

I'm not a fan of single-class-per-file as a rigid rule, but it's not my effect that it has any effect on architecture. Adding a file with a new class isn't substantially greater overhead than adding a class in an existing file, and moving stuff between smaller files is, if anything, easier than moving it around within a single monster file.

For the things I tend to write (CLI apps) deployment is just so much easier if it is all in one file.

I like how it looks.