I never cared for the AT WILL type of thing, This is suppoused to be a CURSE (tho I think of it as a blessing) and as a CURSE by most standards that means not being able to control it in this case
I will never understand once a day free will type things specially with werewolves.
I want to be like walking down a road at night, forgetting that I am even a werewolf (somehow) than BAM!! OH [censored]!
I should think as a werewolf, egging the beast inside you to come out would be easy, its in there, brooding and waiting for its chance to take you over, its the forcing it back in thats hard, which would be a good IC way to explain only once per day, you can only mentally take the strain of forcing the beast back in every 24 hours. The full moon drives it wild, forcing you to let it out.
Its very much a curse for those days that you have to murder somebody