So, time between pushes can be forever?
How many caves have had only one person/team map the entire cave themselves?
Maybe, I should restate my question a little. When you stop extending the line, but there is still cave to go. How long do you get until it's no longer a project? Do you will it to another diver when you die or become a laggered old fart non-diver?
Why don't you just talk to whomever laid the existing line? Discuss your goals and whether you are "stealing" something they have been poised and setup for but are waiting for some reason for better conditions or the stars to align? I think you are thinking there's alot more conflict than reality here...