We're cash rich and calling it profit

Front-loaded rates, generous interim measures, materials applied for ahead of fixing: applications run ahead of cost for perfectly ordinary reasons, and the bank balance swells. Without a CVR nothing distinguishes that swell from margin, so it gets spent like margin - overheads grow, drawings happen, the next tender is priced with confidence borrowed from this job's float.

Early money unwinds by arithmetic: the over-measure corrects, retention holds, the last applications shrink, and the account closes at the real number. The cash was never profit, only timing. The CVR is the instrument that says so while it is still survivable - cost against value, job by job, month by month, with any over-recovery stated rather than enjoyed. The dangerous years are the good-looking ones that were one valuation deep.