Hey there,
In this post I'll try to explain how we can practice with making covers.
If you practice music and search for good exercises, you probably saw many posts. I play electric guitar and I can say that there are thousands of them. But just practicing is kinda boring and music is not about boring, it is about having fun and feeling it. We all listen music also and there are good parts ( good for us ), shreddy parts, hard or easy parts and so on.

If you analyse and take some of the parts from the song or music or solo you want to learn, you can learn many things from them. For example, if you know the Metallica-Nothing else metters solo and you want to practice it, you'll see that there are many exercises in it. Bend exercise, string skipping, melodic relations and so on. So, instead of exercise with boring stuff, why not learning a solo and partializing it?

I have a list to extract meaningful things in a melody/riff/song and exercise them:
1- Create your own backing track: It can be hard to beginners, but nothing is impossible. Just listen and find the chords. Make a meaningful backing track for it. So you will learn everything, just not one part.

2- Don't use any sheets or tabs(for guitars), just listen: try to extract the melody with listening. There was no sheets or tabs 15-20 years ago. Musicians like Petrucci says that they have to listen the music maybe hundred times to learn just one part of the song. What is the result? He is one of the best musicians, maybe the best himself. It is hard to learn with this way, but it will be so much easier when you know how. Pratice with this method like 1-2 months and you will learn melodies almost instantly. So effective when you have friends near..

3- Partialize the melody: With this method, you can create your own language. Just partialize, maybe a solo to meaningful licks ( melodies ). Use these licks in your improvisation and change the key. After that, change the licks as you want and use them. You have your own sentences now!

4-Enjoy: No matter what, it is music and you need to have fun! It is a way to express yourself emotionally.

Stay with music, cheers.