Pencil or No Pencil Lines

Many beginning painters are curious about whether or not to leave the pencil lines of underlying sketches on the painting, or remove. the choice is personal from what i can gather from professional artists. American impressionists like Charles Reid, ("Pulling Your Paintings Together", "The Natural Way to Paint", etc. Watson-Guptill) leaves his pencil lines and they become an importatn part of his painting result and they assist in implying certain edge conditions and detail. Many painters, Eric Weigardt included, put minimal pencil lines on paper with more gesturing motions and large outlines, making them less visible in the final painting. I prefer to erase most if not all of the background pencil lines with a kneaded erasure. Why? I want the final watercolor painting to be as much about what the watercolor is achieving (edge conditions, detail illusion, etc.) and not depend upon another media for those conditions.  Bottom line, personal choice and desired affect--mixed medium or pure watercolor, or watercolor with a slight mixed medium assist (Reid).  Have fun. RK