Yep. When the wild they inhabit is surrounded on all sides, then covering at least three of the four is important for their feelings of security.

As for space, I for one like to give my animals as much space as I have to give...but that also means I have to provide plenty of cover in that space for solitary/secretive species. In the case of my first BP, I started her in her 20L tank when she was 2 months old, but I made sure she had plenty of plants and good hides to help her feel secure. Basically, it worked.