Machinery

Well, as personal preference, I'll stick to my Theme Hospital design of designating areas on the ground that will constitute specific workplaces and not allowing them to intersect. I, personally, want to define that "this 8x8 square will be my workshop" and be restricted to placing only Worksho-specific items in it or general construction items as an alternative. If I want a Barracks, I'll need to define a separate area that doesn't intersect this one.

This opinion is born of my desire a structured castle with separate "facilities" defined either in separate rooms ala Theme Hospital, or at least in separate plots on the ground ala Dungeon Keeper. Personally, I'd prefer to not mix machines from different facilities in the same general space, forcing my blacksmiths to have to pass by my bakers and my candlestick makers just walking from machine to machine. I realise that that's more limiting than just being able to drag-link machines anywhere on the map, but I'm the sort of person who always picks structure over freedom.

Believe me when i say that i dont think any sensible person should mix and match the equipment. It should all be nice and neatly organised how you have suggested purely for efficiency. The only time i may utilise the option to chuck a metalwork in a bakery would be if i want something fast, but dont have the equipment or space, requiring a complete rework of my armoury. In this case, i would just build it in the closest place possible, make the item, then do the rework to get it where it should be.