Several ICs are manufactured in packages with more pins than it supports. For example, the LM317 in an SO8 package has 4 VOUT pins and 2 N/C (no connection) pins. I often want to run traces through N/C pins to ease routing, but wonder if it would make them give up the ghost. If it exists, what is the standard or rule by which manufacturers follow concerning the electrical characteristics of N/C pins? Or do I have to scour the datasheet / do my own testing every time?