The NEC contracts are intended to be concise and where necessary employers can add additions to it or amend the existing conditions to suit their requirements within their organisation or within their industry. Do remember however that the NEC contracts were 8 years in development and now 17 years in existence, during which period the contract has been considered and refined as to what it should contain to make it a balanced contract between the parties. Too many Z clauses are added (often by lawyers!) simply to re-adjust the risk profile in attempt to put more risk back on the Contractor and away from Employer. There is no such thing as a free meal, and the Employer will either pay for this in increased tender price, and/or a lot more headaches for the life of the project. I am just reviewing one contract where it is stated as an Option B (B of Q fixed price contract), yet they have added clauses to make all risk and errors in the B of Q Contractor risk, deleted several reasons for things to be a compensation event, and requested justification of all Contractors costs in terms of invoices, time sheets, receipts etc. Interestingly it seems to be a real mishmash of the principles of options A, B and D which very interestingly is an anagram of BAD!
NEC Training on such a particular project is particularly important so that all parties understand the likely implication of the amended contract on that project, which works really well in a joint workshop early in the project.