A tool is a tool. Doesn't matter if it is closed or open if it doesn't do the JOB.

But if having a closed arranger mind means leaving yourself enough time to actually GIG (and maybe eat and sleep too ) then put me down as one of those...

There are people that like to tinker with cars, build them from scratch, love kit cars, and making the car is the entire purpose. Then there are people trying to GET SOMEWHERE...!

I get the impression that the open arranger mind is like the guy who is more concerned with building the car than driving it.
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An arranger is just a tool. What matters is what you build with it..!