I make my way down Route 29, the Beltway, and Old Georgetown Road five times a week at roughly the same time. Though there are too many cars for me to remember the person I cutoff last week or the driver who rode his brakes, I can count on a regular traffic pattern. Outside of an accident, I know when to expect backups, slowdowns, and idiots who ride exit lanes only to cut over at the last minute.
Does it really matter that I miss a light or get honked at because a NIHer decided to take their sweet old time getting over and not giving anyone a head's up that they're turning left? Outside of being a few minutes later to work, it doesn't stop the earth from spinning, but it is a safety hazard. Okay, a minor safety hazard. Though I expect and prepare for these non-signalers, others may not be so lucky.
Having to slowdown without reasonable notice or caution is unsafe. This is not a situation with unfamiliar drivers making last-minute decisions to changes lanes and turn left. At 7:15 in the morning, we're all locals and we all know the roads. I guess part of knowing the roads is expecting NIHers to fail a basic driving test requirement of turn signal usage.
For the good of traffic flow toward downtown Bethesda and in an effort to practice safer driving, please NIHers, don't be scared to use your turn signal.