Were Argus's eyes gradual or all at once?

Question

Argus has 100 eyes, 50 awake and 5 sleeping all the time. That way, he would be able to keep guard constantly.

But would Argus's eyes have a set time to fall asleep, like 50 immediately going to sleep and 50 immediately coming awake? Or would he have one eye going, right as another would come awake?

Answer 1

Who says half of his eyes were asleep and half awake?

While a number of sources refer to his eyes taking sleep in turns, the only source I can find that specifies how many slept at once is Ovid:

Argus, Aristorides, whose head was circled with a hundred glowing eyes; of which but two did slumber in their turn whilst all the others kept on watch and guard.
_{Ovid's Metamorphoses I, 622-641}

Also, when he is being lulled to sleep by Hermes, more of his eyes close gradually, rather than as a unit:

but Argus strove his languor to subdue, and though some drowsy eyes might slumber, still were some that vigil kept.
_{Ovid's Metamorphoses I, 682-688}