> At 15 minutes a pop you can do 100+ leetcode questions a week.
By that logic, most people would have completed all 1500 LC's in 4 months.
Numbers say otherwise. Each medium difficulty problem takes an hour to solve, assuming you can come up with a non-brute-force solution. Most of them force you to lookup, understand and implement other people's ideas.
If you can do 3 problems a day, completely on your own without any lookup, you're doing good pace.