I agree that most seasoned runners or hikers know what to do on the trail, but there are a lot of people who don't have a clue when someone announces their presence.

I slow way down if there is no reaction from my first attempt to warn them, and even add something like, "how are ya'll doing today?" as I'm getting ready to pass.

I've had a couple of women that I approached and one took the right side of the trail and the other darted across to my left even after I announced passing on your left.

I then laughed and said, "I guess I'm going right in the middle then!"