I think a lot of it boils down to your goals with it, I'm personally very engaged with my user base and take pride in my communication and you may not value that over less work/more dev time. This is also for an internal tool but the audience is diverse (500+ devs, cybersecurity engineers, leadership, writers, etc), I stick with one set of release notes for a few reasons:
- One location, people who may fall into multiple categories (or none) don't need to check multiple places, users also know that all my communication will be via that page/they don't have to wonder if they're missing something
- As much as some detail doesn't matter to certain audiences, I find being able to give all the detail you want a user to know while maintaining readability to less technical audiences is a skill worth developing because the result is regardless of where your notes end up, the person will understand what's changed and why it matters
- Maintaining multiple versions leads to mistakes, at some point you'll leave out a detail to one audience that matters so letting the user mentally filter what they don't care about takes the onus to get it right 100% of the time off of you. I'll often categorize my changes by the section that had the change to help users with this.
- This is a personal preference and you touched on this one but it's just far less work, I've found it common in tech that people don't want to do things more than once or they'll automate it/look for shortcuts and this is no different. This isn't always a bad thing but getting release notes right means your users stay informed/use new features which is why we build them so I think it's worth putting my energy into doing it properly every time