Hello, I try to answer your question based on my experience. Doing virtual contests and then up-solving the questions is a great way of improvement, as you can get familiar with many different ideas with a variety of difficulty levels. But there are two important points that you should make sure you're not missing. The first one is that you might lose interest in competitive programming if you force yourself to do a virtual contest everyday, sometimes you may feel tired and it's totally fine to skip some training days. The next important thing is that although you can learn many different things, you need to make sure you have a minimum knowledge in each topic (which you cannot necessarily guarantee it by doing virtual contests). I hope this helps.

No. Why would you ever believe that practice helps improving your skill?