You can't cross a river unless you have an established "beach head". I don't know what RU is thinking because it seems they are ignoring basic battle tactics.
Yeah, either they are really poorly trained, or they have bad intel (underestimating Ukraine troop strength or positions). Maybe both. I also think that this was one of those things where their command protocol fails them so badly because the troops don't really have a lot of room to improvise as the situation on the ground changes.