I rarely do the elbow movement for picking, unless I'm jamming with some chords may be, but it's very unlikely to me for shredding...

I believe that the main theory behind speed, is to play every thing with the least amount of movement/energy , so it's like saving your energy for higher speed...

Take a look at Malmsteen picking and over all playing style, he usualy looks as if he's not making any effort to shred, and usualy he uses finger movement for picking, rarely uses his wrist,and never uses his elbow...Also Michale Angelo play almost the same way.

I'm not very good at medical science to tell wether the elbow picking is dangerous or not, but i think if it doesn't hurt then it's ok.