Leetcode's business model is completely at odds with interview prep. They want you to prepare for as long as possible, when the goal should be to prepare for as less time as possible.
It's in Leetcode's interest to keep you engaged. The more you stay on the platform, the more likely you are to buy a Premium subscription. The longer you hold a monthly subscription, the more money they make.
Wait, isn't that wrong? Shouldn't their goal be to get you prepared for tech interviews?
Wo! Hold on. What made you think that was their goal? They never stated that. It's just what people assume. Their goal is to make money, not to get you job offers.
Let's say you want to design a site that people keep using. How will you design it? You will keep people thinking that they're inadequate in their preparation. Then you will give them something to do that makes them think they're making progress. But just enough so that they come back the next time.
Feels familiar? Well it's not very different from social media companies like Facebook. Keep people engaged, keep giving them the dopamine hit. Keep them thinking they're being productive.
Still don't believe Leetcode would do this? Ok, let's take a look. When Leetcode got popular (around 2016), it had ~100 problems. That's why it got popular. It was one place where people could solve and see 100 problems. These 100 problems were well-picked.
Then, they started adding more and more problems. Now, they have 1500! 1500 problems for interview prep? That's ridiculous. Even they know you won't do most of them. Yet they claim to be the best resource for interview prep. It's making them money. The more problems they add, the more people spend time solving them and purchase premium subscriptions.
If they really cared about interview prep, they would've restricted problems to 300-400 at most. They would've focused on teaching you how to solve problems, instead of constantly adding more and more. But that would mean less money, because people won't come back to the site. They'll learn and leave.
What is one way to keep you coming back? Keep giving the illusion that you need to prepare more.
But that's not the most scary thing about this. There's something even scarier - their Hard level problems. Read about it in this article
Fortunately, as long as you're aware of this, you don't need to worry. Follow fewer problems, focus on mastering them. Don't be bothered by the 1000+ problems on these sites. I explain one time-tested approach in this article