It's very hard to predict (I'm at the mercy of my clients and their drawing borders). That is why I asked if it would be possible for users to create their own associative fields by some means - then we won't have to keep bothering you!
I appreciate that this may be a difficult wish to fulfil, but it would at least give me some future-proofing.
I find the whole method of placing, creating and populating associative fields in SC very 'unsure' at the moment. The process to follow doesn't flow very well (i.e. it lacks some logic, placement of the boxes is imprecise etc.). It would be nice to have some sort of table to call up showing all used associative fields and what they are linked to. Something like that would gather the work flow into one place, make it more manageable and give the peace of mind in knowing that you've got everything hooked up.