As you point out, this very definitely does have a lot to do with precisely how the CGI app is structured. For example, there really are some sites out there which define a bunch of independent (Perl) scripts ... instead of a single “application” ... and, although they technically do “work,” this approach is really not compatible with FastCGI.

Balooney, doesn't matter over how any files its spread, its as compatible with fastcgi as anything else