Yes, when I’m using the ‘map’ screen for navigation, the 510 often gives me turn instructions based on significant changes of direction, such as a sharp bend, even if it’s not a junction. It has no knowledge of the actual road layout. (I have turned the beeps off because they’re too irritating.)
It is possible to manually program it with proper turn instructions but it’s more trouble than it’s worth. As noted already, I get on fine following the breadcrumb trail.