A blink has about 3 to 4 states.
State 1: Fully opened (O)
State 2: Closed tight (C)
State 3: 3/4 opened (O1)
State 4: 4/5 opened (O2)
Common sequences (at about 0.415s per state):
Conclusion: Requires least work but jerky animation.
Sequence: O -> C -> C -> C -> O1 -> O1 -> O2 -> O
Conclusion: Pretty convincing.
Conclusion: Would be better if there is one more C state.
Conclusion: Too linear(?)
Can anyone guess