I started off avoiding mod.rs because it’s the old way and I prefer having the module name as the filename. However, if the module needs a folder for submodules anyway, then there’s a reason to tuck it away as mod.rs, especially if not doing so leaves lots of duplicate names (a.rs, b.rs, c.rs, …, a/, b/, c/).
But then I don’t really like to have much else in mod.rs other than mod declarations and pub use. Maybe a utility fn or a not-unwieldly implementation of struct “Foo”, the module’s namesake.
You can always inline the mod.rs contents in its parent module and have one fewer file overall. Not every module needs to be in its own file.
But generally when working in an IDE I don’t like to see a bunch of mod.rs files in the tabs as it just makes it harder to jump to the right one.
I did that at work and people had a heart attack lol. Which i thought was silly because the mod literally had no code in it besides module file declarations. /shrug