IMHO
Short commute = wear street clothes and not need a shower, no water bottle.
Medium commute = bike clothes and freshen up (not necessarily shower), 1 water bottle.
Long commute = mandatory scrub/shower and serious concerns of extreme weather. Fatigue builds through the week. 2-3 waters.
XL commute = rechargable battery dies before getting home, backup battery or recharge at work needed. Rest days needed during the week. May need stop to refill water bottles. Need to have snack available.