Spending a week practicing leetcode puzzles is what's actually being tested, and that's actually not a bad metric for judging employability. It's a relatively trivial exercise to sit down and study. If you can't do that you might not be right for the job.

It sounds inflammatory but nowadays the ability to that is quite a valuable skill.

If most jobs use it as a test then it's just something to game and you are not testing "someone studying for a week". You are not testing anything.

If you want something like that give them something novel to your industry for both of you to study.