It depends. My backyard lawn is about 2 acres in size. It takes me 1.5 hours to manually mow it with a small 21 inch powered push mower. I just let the auto mower do its thing continuously and it charges itself. Costs almost nothing since I sharpen the blades about once a month myself. It’s also nice because the grass is always trimmed. You don’t have to go through the let it get tall and the landscaper mows it down every two weeks cycle.

That's part of why tech products disappoint. The MO is to reduce a complex problem to a simple base case (our robot can vacuum an entire house provided you have no stairs or furniture), half ass solving the complexities, and market your product as if they don't matter.

I'll continue doing stuff myself or paying humans. My time is too valuable to waste on empty promises that tech will save me time.

says the guy paying someone else to do it