I don't announce my presence, because frankly I don't want the slow-moving randos in front of me to know I'm coming. Because 9 times out of 10, they will look over their left shoulder, and in doing so unconsciously drift to the left, which is the location I will be occupying momentarily. I'm usually doing 6-7mph faster than the typical rider on the trail, so 9-10fps. I'm past the slow traffic in less than a second. I see absolutely no need to turn it into a whole "thing."
Disclaimer: My trail riding is about 80% on the northern SART (Santa Ana River Trail) which is basically a freeway for bicycles. Bikes only, and no posted speed limit. Top Strava segment speeds ~30mph.
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