Right. We have no idea how another species perceives time. This could be nothing to them.

And even if they do perceive it like us, that hasn't stopped humans from great projects. How many generations did it take to complete Stonehenge or the Great Wall of China? We're still on top of Voyager too after 50 years.

of course by the time we had the ability to do von Neumann Probes our anthropomorphic assumption of time scales may have changed.

How much would human life span need to increase for a von Neumann Probe to seem reasonable. I would think a life span of 600 and you're thinking, sure I won't get to see it through, but my allotted genetic offspring that I am allowed at age 500 if either of my other two have failed might.