I play in an amateur wind orchestra and I noticed that generally people do not play from memory at all and look into the sheets for the entire piece. I'm no exception for the most part but here and there I tried to lift my eyes up and remember the piece in my head - usually failing after just a couple notes and getting my eyes back to the sheets quickly. Now when there are critical points of the piece like changes in tempo for example people will keep an eye on the conductor but usually we'll quickly get back to looking at the sheets.
Now I've heard that in professional orchestras many players can play quite a big chunk of the pieces from memory. But are there any advantages to that? I can see that you might be able to keep a better eye on the conductor but even when looking at the sheet you can still get a glimpse of him at all times (though that can depend on your seat). And I also do see why you should learn a solo piece from memory. But as for our amateur orchestra, we are never in a position where we do not have access to a sheet in front of us. Not even when playing solo pieces.
What are the advantages of playing from memory? Isn't it much safer to just stick to the sheet? Do professionals actually practise playing from memory for an orchestra piece or is it just a side effect from playing the pieces a lot? In an actual performance do they play from memory even if it's not a solo piece or do they play the "safe game" for the entire piece?
Should I start to actively practise playing from memory when playing in an amateur orchestra?