I ride on a multi-use paved trail quite a bit, and I try to warn pedestrians and other cyclists when I'm approaching, and also slow down a lot under certain circumstances, especially if there are pets or children up ahead.

One situation that has come up multiple times, occurs near road crossings, where this trail has metal posts set into it, presumably to prevent cars from turning onto the trail. Typically there will be two or three of these metal posts, spaced three feet or so apart, so there is just enough room to ride your bike through. This creates three (or perhaps four) "lanes" in the path.

On more than one occasion, I've been approaching a walker from behind, and the walker is obviously headed for the rightmost "pass-through" between the posts. If someone is also coming the other way, then I will try to ride through the middle pass-through.

But sometime the walker is using the metal posts as their turn-around marker, so to speak, and so the walker will walk through one pass-through, and then, holding on to the post, they will do a quick U-turn around the post, to come back on the adjacent pass-through. (Which is sometimes the one that I'm trying to ride through....)

Calling out "on your left" doesn't always work, so now if I am approaching a set of these posts, I wait for any pedestrians to go all the way through and keep going, before I assume I can use the adjacent slot.