Q1) What is the best technique to practice questions without wasting time, like if i practice a lot of questions but they all are easy so its basically a waste of time.

Q2) How do you guys practice..? Hoe many hours do you invest in competitive programming per day..?

Q3) Also is codeforces a good site to practice problems from or are there even better websites..?

Q4) Are A2OJ ladder question worth doing to improve..? Because i saw many of its questions are from very old codeforces contests.

I just want to clear some of my doubts and also i want to ensure that if i am spending my time practising, it should be worth it.

Sorry if you don't like these type of questions because i am sure that they are asked a lot. But i just want a clear roadmap that i can follow to master cp.

Thank you.