We're about to submit and nobody has checked the price
The rates cover the work, but maybe not the downtime, the prelims, the waste or the risk, and we find out which after we've won it.
What's happening?
Tender deadlines do what deadlines do: the last week goes on chasing quotes and finishing the build-up, and the check that was always going to happen at the end gets squeezed into an evening or skipped. The rates get eyeballed by the person who built them, which is not a check; it is proofreading your own letter.
The misses are predictable, because they are the costs that don't sit in any one rate: downtime between operations, prelims running longer than the tender programme admits, waste, attendances, the risk items everyone means to price and nobody owns. Win on a number with one of those missing and the job starts behind its own budget - and the gap surfaces slowly, month by month, where it is hardest to argue back.
A pricing review before submission is someone outside the bid walking the build-up: rates against quotes, allowances against the programme, the gaps named while there is still time to price them.
The solution
The build-up walked by someone who didn't write it.