Yes, you can weed out 50% of incompetent applicants, but that is not the issue. The problem is that the people who will excel in these questions are the ones playing the leetcode game for months. The people with real jobs will pass your question but will do so-so compared to the leetcode gamers, and the second group will get the job. Also, doing exceedingly well in the coding questions doesn't guarantee these people are any good at the real job.
My last "1 hour" test took me hours to complete. I asked them to implement it in front of me in an hour and they couldn't.
Programmers are terrible at estimating and programmers will choose tasks that are obvious to them because it's the exact thing they do every day, but it might not be so easy for people not in their exact niche.
