That's where I download it from myself yesterday evening.
I can't speak for 19.2 (downloaded but not installed), but 18.3 had a large number of updates waiting once installed. For someone fairly new to Linux, this made me a bit uneasy about going with 18.3. As it is, I installed the default selected options (levels 1 & 2), but other than the level 4 kernal update that I installed, I still see quite a few level 3 and 4 updates sitting there.
Lol, yep. I explained why in my PM this morning, but to share again with Legend... 18.3 is like 3 years old, so in the meantime the ISO, packages, and applications have been updated all along since the distro was boxed as a download package. It now has a lot to catch up on to be up to current date the first time you update it after installing.
After the first time it will only be the very few occasional updates. But that first one is huge to truly bring it 3 years up to date. They can’t really update all the archived mirror downloads out there, it would be impractical, so it has to catch up on all that after it is installed. :)
You can go into “edit/update policy” in the update manager and set it to “just keep my computer safe” and it will then only give you the critical updates. :)