@ECMO3 did you basically run this as a direct series of short dungeons, or did you fill in with a broader campaign? I'm only asking because 4 months or so seems really fact for 20 levels.
We did it as part of a larger campaign. This group has played a lot of 1-20 5E campaigns. Probably around 10 or so (I have lost count). 4 months is actually about average, maybe a little above average for a non-XP campaign for this group.
I am in another 2024 campaign as well that we started the same week. That is a Greyhawk 1E series redone for 2024. It is Temple of Elemental Evil-Scourge of the Slavelords-Against the Giants-Drow.
This one is XP based, we finished TOEE and are almost done the first location in Scourge of the Slavelords. We are 10th level which is high for where we are in the campaign (designed for 7th I think), but that is how it rolls sometimes in an XP game.