This is a lesson I have learned the hard way so take my bitter experiences and consider it wisdom derived from idiocy.

The lesson is simple. When creating an option set, unless you are ABSOLUTELY certain you do not need to, make it a global one. Even if you are absolutely certain, make it global anyway.

The consequences of not heeding this advice are almost as injurious as spießrutenlaufen. If you have ever had the displeasure of trying to get a workflow to pass a value from one entity-defined option set to another, a row of soldiers with pointy sticks will not seem too bad an alternative.