On the Timeline menu there is an option: Insertion > Insert Clip Zone in Timeline (overwrite)

What exactly is this doing?

I didn't know but I just tried it. Say you have a 10 sec. zone defined on a clip in Clip Monitor and on the timeline you have a 20 sec. zone defined somewhere. When you press "V", it will insert the 10 sec. segment of the clip from the Clip Monitor at the beginning of the zone on the timeline. If there happens to be another clip there already, it will overwrite it, completely or partially, depending on how long the existing clip was. It doesn't seem to modify the duration of either zone when doing it.

Does that sound right?