I use my 2014 MacBook Air in clamshell mode, connected to an external monitor. I have it set so that the monitor shuts off after 15 minutes, however, I have checked the box next to "Prevent computer from sleeping automatically when the display is off". This seems to stop my MBA from ever going to sleep mode. I like that because backups still work and downloads/uploads still continue. I'm just curious if it's ok to have a closed MBA connected to an external monitor and external power not go into sleep mode?