My preference is to cut back the working side so it extends only 5 to6mm beyond the part that's around your thumb.
Also, the angle at which you trim, is important. BEFORE you trim, look at your (picking) hand position. I like to leave the longest part of the pick at the outside edge, because of the angle I hold my hand. The trick is to make sure the part that PICKS the string is more or less at right angles to the string, as you hold it. YMMV.

Rich McCarthy