Words of Champions was the first Scripps-provided study list, and it preceded Paideia. A new edition of Words of Champions released yearly, each of which contained little over 3000 words. Every year, about 550 words were rotated in and out of the list. Anyways, it’s pretty old. However, it’s definitely still relevant, and has plenty of very good words. This list has consolidated the words used on past editions. The hardest words from this list (Final and Intermediate) would probably show up as Regional Additional Words or in the earlier rounds at the national bee. I’d recommend at the very least giving them a look.*
*Thanks to the user “Schola”, who gave helpful information pertaining to this list in the comments!