For example, TreeSheets is released quite frequently (sometimes daily; see releases), the last update to its Nix expression was in January 2022, so an update would be timely, but what if there is another release tomorrow?
Also, I’ve been keeping it simple to run the latest versions by doing the following:
Personally I use overrideAttrs to override the src in my config, so I don’t need to have a local clone of nixpkgs that I maintain. I also tend to add such packages to systemPackages, I’ve not come across one where I both cared about the version and didn’t want it permanently installed.
Both are valid approaches, though, especially if you already maintain a downstream nixpkgs for other reasons.
As for update frequency, I think that’s a better topic for Development than Help
My personal opinion is anything security related ASAP, everything else whenever you (read: the maintainer) see a need/desire for it or close to feature freeze for major NixOS releases, whichever comes first.
Daily updates would probably be more likely to annoy your users than actually help them.