for eos, the answer is a MUST.. but for Selene, the asnwer is it's optional.. sometime i just let my Selene to do anything that she want because when i put her on Obey, sometime i just forget to click Fey Glow or Few Light.. or Selene probably can silence something important too automatically.. (actually it's very hard to silence manually by using Selene).. but i usually will switch between Sic and Obey when using Selene..