There shouldn’t be any difference if you kept your system updated, other than that you may have installed extra packages in the meantime. If you’ve kept the system up to date and have properly merged your .pacnew files, then there’s no point in reinstalling.
My system here was installed in April 2019, and I’ve never had to reinstall. That’s the whole idea behind a rolling-release distribution.
hmmm, I was having a years old install and the timers was the same as first installation…
When I install the 22.3.1 and the 23.0.1 the timers was changed
I usually merge the new .pacfile, and keep always updated (stable) the system
Well, it doesn’t do that by itself — not out of the box anyway, because that would be a bad idea, and for so many different reasons. You have to keep the system updated yourself.
There will be an indicator in your system tray whenever there are updates, and you should also subscribe to notifications for the Stable Updates category, because with the exception of urgent security patches and bug fixes, updates are bundled together, and they always come with a dedicated announcement thread, the first post of which details the changes, and the second post of which tells you about any potential problems and how to deal with them.
This sort of thing is commonly discussed on the Stable Updates threads. All the more reason why you should keep an eye on them.