>"Most engineers (including me) spent months grinding LeetCode ..."

I have not done it once (work in programming for 40+ years) as independent. Few times potential clients tried to play this game but I just simple refuse. On was surprised and asked why? My answer was - I have a track record of successful deliveries, here is big list of projects, emails and phone numbers to confirm. If you are going instead to rely on some tests to prove my abilities I have better things to do then be a schoolboy on exams.