I'm playing through the scenario where the volcano goes off ever so often and wreaks havoc on my buildings. Question is; would an additional construction office help in faster repairs?
Or none of the above?
That depends if you're talking about if they are only on fire. Or if they get 100% demolished.
Scenario #1: The Mine/Building is on fire, firefighters put out the fire. The building will rebuild on it's own over time. The punishment here is that the longer it takes your firefights take to put on the fire, the longer it's going to take to repair it's self.
Scenario #2: The Mine/Building gets completely demolished. Then yes, more construction offices would improve your chance of rebuilding the Volcanos destruction.
But it should be noted that if your Teamster Port was destroyed or on Fire. Then your construction crews CAN'T rebuild until you fix that problem first.
If you had a construction office, on the volcano island (which is unwise) and it doesn't get destroyed or put on fire. Then it will start rebuilding your industry much faster.