When is it appropriate to rename a file?

[Jesse Gibbons]

There are a lot of files in gnu/packages/, and some of them contain only
one package. If I want to add a package with a similar function to one
of these solo packages, is it appropriate to rename the file? In
particular, I want to rename jrnl.scm to journal.scm and add a journal
application to it for better organization. 

I also want to note that the more I examine gnu/packages/*.scm the more
I see a serious need for refactoring.