Don’t read too much into blog posts. This is engagement farming to capture search traffic and trending topics related to LeetCode.
Taking months off to grind LeetCode all day isn’t common and doesn’t even make sense. LeetCode can be done on a lunch break. Even one problem per day in the evenings is more than enough for a senior to prep for an interview.
Having done LeetCode, I’m not even sure how a senior could justify spending 2 months doing all of the problems full-time.