If it's a collared overcoat and the weather is shite, yes. If it's a polo or collard work shirt and the hot sun is beating down in the middle of summer, yes. Otherwise, no.
In summary, pop your collar for function, not fashion.
I used a hypnosis recording designed to stop the urge to bite my nails. Recorded by Bonetti-something. I listened to the recording on my ipod before bed every night for a week or so and then went to sleep.
Haven't bitten my nails since.