Composer said Ugh.  The responses so far have been nonsensical to be kind.   There isn't any grey zone in violin like a piano.  You either are competent or no one will want to listen to you.  Anything less than 4 hrs/day practice is basically a waste of time because it requires intense concentration that can last at most for 20 minutes at a time.  And then you need a substantial break to relax.  So 4 hrs turns into 3 hrs right off the bat.  Take 1 hr for tone production, and 2 hrs for scales and arpeggios and the day is done without consideration for a lot of misc stuff that has to be done as well. What can you do in 60 minutes?   Pulling a good tone from the instrument is impossible...talent is not even an issue.  I'm not making this stuff up.  A professional soloist will have practiced 8 hrs/day for long periods of time.   Its slow going ...Dorothy Delay said as much..."its time consuming".
There are a lot of "grey areas" when it comes to the violin just as any other instrument. There is also a big difference between getting good enough to play in a community orchestra versus becoming a professional player in a professional orchestra or a great soloist. There are many different variables involved. Different community orchestras have different requirements for membership, some require auditions, some don't and there will be a large degree of skill variation and competency among the members. Some players will be highly skilled and can play every note in every piece perfectly regardless of tempo. Other members may be near beginners and not capable of playing every note and/or may onl;y be able to play less complex pieces at slower tempo's, etc.  And everything in between. Also,m for each indivuidual player his/her skills and abilities will usually improve over time depending on how much time is spent for practice, building technique, etc. It also depends on the type of music being played i.e. difficult, long and complex symphonies versus simplified arrangements or simpler tunes, etc.

I play in a community orchestra and I see this regularly. Most of what we play are classical compositions as written by the composers. Skill levels in the violin section alone are quite varied from player to player. Yet we manage to make some very beautiful sounding music that people enjoy listening to and we enjoy performing for them and working together as a group. That is what is important.  If we were a professional orchestra then the playing field would be quite different as would our expectations both as individual musicians and collectively as an orchestra.

Composer said

It takes about 7 years for an adult self learner to play the violin well enough to play in a community orchestra.  Now, my contribution is rock solid.  Pierres, is a bunch of hand waving.

Hmmm.... lets see. I play in a community orchestra and I think our orchestra has clearly proved the above statement wrong.  Yes, we do have some people, like myself, who have played all or most of their lives and who have had formal lessons We have some who have played as youngsters and haven't picked up their instruments in 10+ years and we have some who have been playing no more than a couple months. Yet put it all together and we sound pretty damned good. Good enough to play quite difficult music at concerts and have people really enjoy what they are hearing. can we match a pro orchestra like the London Philharmonic ?:Hell no. But we can play well enough to bring happiness to people and bring everyone a real sense of satisfaction. And  the critics have giving us some rather good reviews. And yet, we do have adult self learners with far less than 7 years violin experience.

I know I have already harped upon this but I have a thing about patently false statements.