That's for people who want to help with development, debugging, and validation of this open source project.
For us regular users it's best to stick with an "official" and "stable" release.
New/unproven software can have new (maybe unknown) bugs or something may have changed that's not yet documented, etc.
My Arduino shortcut points to arduino.exe.
I don't even know what version I'm running and I've never had any problems/issues so I've never NEEDED to update.
'Dunno... I haven't even looked to see what's there (except for the example code).
Sometimes at work (where I don't usually have an Arduino) I'll write a small program or make a small change, and then I use Sketch -> Verify/Compile to check for syntax errors. But of course, without connecting an Arduino and running the program you know if the program is doing what you want it to do...
I have no clue what "revisions to IDE public versions" and "tracked internally" means.
The hourly build is made from the tip of the master branch of the repository. So the Git commit hash you see at the top of the list of commits at the link I provided in my last reply.
The release versions were built from the Git tags you see here:
Neither do I. [Recall I am a new to Arduino]. Because I proffered a "nonsensical" question, I got the impression IDE version identifiers nonsensically remained unchanged for long periods. Being unfamiliar with Arduino I used vague language to describe my vague understanding. Also being unfamiliar with your forum architecture I did not pick up on the Commits links you were providing until now. I now understand. Thanks for your yeoman effort to get me on the right track.
Well, there are sometimes fairly long intervals between releases.
The main focus is now on the Arduino IDE 2.x series, so the development on the 1.x series is mainly only for essential maintenance. The last three releases were made in response to the user concerns that the IDE might be affected by the Log4Shell vulnerabilities.
In fact, if you look at the commit history, you'll see that the hourly build is essentially the same code as the 1.8.19 release.
Perhaps I should comment that after 40 years of programming experience, and about 15 of playing with Arduinos, I have never, ever, had either the need or the desire to run an "hourly build" Arduino release.
That may be because I think those are mostly for "automated regression testing" (to make sure that no one accidentally committed a patch that causes some obscure piece of the code to stop compiling.)
Or it might be because Arduino has been careful about labeling "production" releases, and there's never been a seriously broken release. (The flip side is that development can be slow, and Arduino can be very conservative about accepting patches and/or requests for new features.)
I'm the opposite. I only ever use the production releases when I need to reproduce the environment of someone I'm helping out here on the forum. Other than that, I use the latest build. But that is only because I want to help out by beta testing. For anyone who only wants a stable tool to use for working with Arduino sketches, I strongly recommend using the production builds.
I'm not aware of any use of them by Arduino for automated testing. My impression has always been that these builds are made for use by human beta testers.
The automated testing systems tend to make their own builds. For example:
I can't show an example for Arduino IDE 2.x because it doesn't have any automated testing against the build (only some unit tests against the code), but that itself is clear evidence that the sole purpose of those builds is for the convenience of human beta testers.
It may be that some 3rd party projects are doing testing against the hourly/nightly builds though, not primarily to find problems in the IDE itself, but rather to identify in advance breaking changes so that they can prepare for it before Arduino makes a release.