Yes, they are.

What are some of the most common mistakes made by violin players?
Many of these can be attributed to having a poor memory and poor instrument skill. A general rule of thumb is that in a good memory, a violin player can remember approximately 70% of what the strings are (and about 70% of what the strings are not) whereas in a bad memory the player cannot recall 60% of what the strings are (and about 40% of what the strings are not). It can also be said that a bad memory will cause him to not play the violin exactly the way it was intended to be played. (This is only true for the very worst violins and violins that are very badly carved.) Also, if the instrument is worn out, or the player is very sloppy, the instruments play different than when used to their fullest potential.
How much time is required to master a particular instrument?
One of the most important qualities of a good violinist is that he does not learn music by spending hours at the piano or the violin. This is especially true if he is going to be asked to play many instruments. The time needed to master a violin is about the same as the time it takes to master a piano. For example, I have been playing violins for 20 years now, all in different styles with different amounts of practice. There is one point of common understanding I do have though. It is very important to not forget to practice the instrument properly, as well as practice the parts to be played. It is also important not to forget to practice in front. It is more important to know what is the instrument you are playing at any given time than it is to be ready to play in the same spot all the time, especially in the worst situations. The key is to practice.
What kind of exercises can use the time you gain from your practice routine?
I encourage every violinist to learn how to bend the neck with the bow, how to use the strings, and what to look for in the case of broken bones. I have many friends who play only stringed instruments for their enjoyment and it takes a long time to learn enough about the different types of instruments to be able to play in concert.
Is my practice routine going to change as I get closer to becoming a professional player?
There is a lot of overlap between the kinds of players that become masters. One of the reasons they become masters often is that they
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