I just had an email correspondence w/one of the managers on my team in which he apologized for over-abbreviating. There's no such thing as far as I'm concerned. Any time you can save a fraction of a second by avoiding a keystroke, I'm all for it! Here's why:

MST P#PL SHWLD B #BL TW RD THS SNTNC FRLY #SLY WTHWT VWLS