It seems clean if we categorize things in directories.
spec/pdf/ section1.pdf, section2.pdf, section3.pdf spec/doc/ section1.doc, section2.doc, section3.doc spec/txt/ section1.txt, section2.txt, section3.txt
However, you have to type “pdf” twice, and the path gets one step
deeper. Instead, we can just flatten the directory.
spec/ section1.pdf, section2.pdf, section3.pdf section1.doc, section2.doc, section3.doc section1.txt, section2.txt, section3.txt
Note that it is as clean as the previous one because the files
are named nicely. And it is a lot more accessible.
Do not afraid to have many files in a directory. I say it is OK to
have 100 files in a directory as long as those files are categorized
by its name. Both UNIX’s ls and Windows explorer sort the files.