Z clauses....thinking about them from a different angle (part II the justification)

Having established the mischief and everyone being comfortable with that, I wonder if we can bring a simple scientific test to help justify the need.
Hopefully there are challengers in the drafting team and we are not letting people loose with blank cheques to write z clauses, so the challenger(s) says:
1. What is the likelihood of this mischief actually occurring on this project (somewhere between 0% and 100%)?
2. What would be the severity of this if it did occur (try not to complicate, 1st go at this just think about additional cost the client might be put to) - order or magnitude, is it £1, £100k, £1m or something else?
3. What would be your fee to write the z clause, write a corresponding guidance note and set of flow charts so all are completely clear what it addresses and how it fits into the rest of the NEC3 contract?

You must by now know where by stealth I'm going here.....if 3 in £££ will cost more than the £££ of 2 x the % of 1 then only the z clause salesperson will be better off. It would be cheaper to give half of the sum of 3 to charity and can the proposed z clause.

So this part of the note is making sure there is justification, the proposed z clause not only has merit but also is financially prudent. Funnily enough, this is now looking like a business case!