Grinded

These are new grad positions non-FAANG companies. I've taken maybe about 14 OA's in the past 3 months and only 1 or 2 were DSA questions from Blind75/Grokking. The rest of them were Strings and Arrays. Where is the best source to practice Strings and Arrays? Grokking, Blind75 and NeetCode all seem to center around DSA FAANG questions. Do I just do all 500+ Strings and Arrays from LeetCode?! There has to be a better source somewhere out there that will help me identify the patterns rather than doing all String and Array questions from LC.