It looks like the next patch is supposed to remedy this a little bit:
https://eu.4game.com/patchnotes/lineage2/206/
That's for EU, but it's assumed it'll trickle down to us suckers in NA at some point. Feoh, Yul, and Wynn will use Blazing Swamp for 40K, while Sigel, Tyrr, Othell, Iss, Aeore, and Ertheia will use War-Torn Plains.
If NC used a better design for the Mentee enchant scrolls, the issue of crowds in these places would drop. I see groups of five regularly in Swamp with toons that are all similarly named (even like Earring30, Earring31, etc). At the same time, isn't this the same design EU, Russia, and other regions would be using? Do they have extreme lag like we do? Is NC North America just cheap with server hardware?