This has even been the case where the job is going smoothly, there are no issues, and the promise comes 'out of thin air.' The work never materializes.
This is because the day before, the GC realized his profits were still at 50% not the usual 40% and was wondering if you forgot to hit him with a change order or something. He was doing a "Just in case" carrot dangle.
This technique is spelled out clearly on page 857 of the GC/cheapskate handbook (Mcgraw Hill 1978)
