In the limit one could have a single header file for the entire gamut of the C standard and one for Posix. Who can recite even a tiny fraction of all the functions and constants in those sources? Such fat headers overstuff the namespace, making it all too easy to step on accidentally. As a rule of thumb, I'd say a header with a hundred entries stresses the limits.
I don't put much store by arguments about the effect on compilation speed. Doug
