There is no hard fast rule that says manufacturing = standard. I am not sure Microsoft would back this up in a written statement. Whilst “traditionally” manufactruing companies would use standard and set these for the year and cost account variances I have implemented many manufacturing companies that have not used stadnard. The question in case here whilst utilising manufacturing is actually more like project, the length and term of these projects would seem to make standard costing fairly redundant if they remain static for the year.
That said the accountant of the business should be driving this. They should understand the reporting requirements of the business financially and decide upon the best costing method for the business, then implment a system in this manner.