#DailyBloggingChallenge (190/200)
The two panel setup makes sense if the windows are long and one has space on both sides for the curtains. The one panel setup is better for smaller windows and sparse space for the curtains on either side of the window.
The blacked out functionality is great if sleeping in a light polluted neighborhood. Though can prolong waking up since not in sync with sunrise times. This is where the shower curtain comes in having light show through while giving privacy.
#DailyBloggingChallenge (191/200)
Blacked out vs light permission depends on the primary functionality the individual desires.
Further with an aid of additional tools one can achieve similar effects. For example a smart bulb or light alarm clock can simulate sunrise. Or an automatic curtain opener can help getting daylight in.