Before I started my estimating consulting business, I bid projects for a general contractor. We bid projects from $100,000 to $10,000,000. I tracked OH&P and General Conditions as a % of the total bid for each job.
General conditions, or job site costs, would run from 8% to 15% from small to large projects. Usually around 12%. Larger jobs take longer, so the cost per month was for a longer time and the % of total didn't change much. OH&P, profit and off-site costs, would be set at 5% to 7% depending on the size of the job and the complexity or potential liability in completing the project at the budget.
I found projects above the curve of the two percentages added together, 13% to 22%, based on the size of project, were usually won by another bidder. I agree with you that a job taken over from a defaulted builder would make that liability cost at least 5% higher and the warranty of covering work already completed might be another 5%. It might take 5% just to get previous work to pass inspections.
So much depends on the % of work already done and inspected, existing subcontracts and if they will be honored. In other words, how much new risk is being taken on. The original builder/ owner didn't have construction profit in his budget, he wanted his mortage as low as possible. His profit was to be from rent income on an appreciating project with a depreciating tax base. A new builder with no ownership value, and only construction profit is going to need a higher % OH&P.