Do I need Cad specs?

I'm being contacted lots of late to ask if I can make CAD specs of your shoe designs. Just to clarify, it's not always necessary.
In the world of fast fashion, there usually isn't time for a designer to make cad specs, so they send hand drawings to the factory. In the world of luxury fashion footwear, it is most unusual. Did you ever see uber shoe designer Manolo Blahnik with mouse in hand, working on his specs? Nope?
My advice is to ask the factory how they prefer to work, perhaps if they can provide you with the kind of spec that they are happy to work with. Then if the answer is 'CAD spec', it's time to enlist that freelance footwear designer to help you.