I have a Schneider 180mm in a Copal 1 shutter. I was shooting over the weekend at sunrise and ran into an interesting problem. (using Type 55 Polaroids)

If I shot at f8 for 1/2 second my polaroids were fine. If I shot at f11 for 1 second they were drastically over exposed.

The speeds all seem correct by sound but apparently the 1 second speed is off. Prior shots seemed ok around 1/60th and 1/125th.

Questions:
How often do you shoot 1 second exposures?
Is it worth getting it fixed or replacing the shutter for 1 false speed?
Are shutter irregularities just something you get used to, and compensate for?

thanks in advance