You have to allow enough time for the >10 km between the Guggersbach bridge near Zumholz Plaffeien and the Sodbach in Heitenried, since the subsoil is of course not a hiking trail in the usual sense. The Sense has to be crossed dozens of times during the hike in the river bed, and this is only possible in wide places where the water is shallower and flows more slowly. Otherwise it tears your feet away on the sometimes slippery stones in the water.
For a hike in the river bed, it must neither rain nor have a thunderstorm warning in the mountains higher up. The scythe quickly swells into a raging mountain river. So always only into the riverbed when the weather is nice and stable in the Schwarzsee and Gantrisch areas.