What is funny to me is that once the plan was drawn, much of the usefull "hard" work was done. Humans are not perfect like robot so it is pointless to try to find the "perfect" path, in any case, mistakes will be made. It is also solving for the wrong thing, there is not much benefits travelling less distance, but minimising time spent on the task is the real problem. For those sort of tasks, it is very much like driving: the shortest path is not necesserally the fastest. Another very important point is that ease of application is of prime importance, it's not very usefull if you need to think hard about which way you should go just to minimize distance, it increase task complexity tremendously for no real benefit.

Considering all that, it is obvious that the real winner solution would be just look at the map and draw a path by hand, using human intuition and heuristics as an algorithm. Even if you would have to make a few corrections, this could be done in minutes instead of hours.

But of course I understand that the point was really to find an application as an excuse to practice working with optimisation algorithms. In that sense, it is a well done job !

Now for how "normal" humans would do it: they would try a few ways and settle on an approximate optimun depending on how much time each pass took and how easy it was to complete. The thing about those sort of task is that they are not really uniform (some places are bound to be dirtier than others and it is easier to approach some features in a certain way), so a naive optimisation like that is unlikely to be what's truly needed even if the solution is technically perfect.