An early bid for a new Filiberto's location went out as a full general contractor number, off a plan set that was only three sheets, no structural or mechanical drawings behind it at all.
I reset the scope down to shell labor only: slab, footings, wall install labor, structural coating. Material passed straight through to the owner, everything else named and excluded. I held the full turnkey number back for a later stage, once we had a complete plan set and a site walk.
Standing behind a full turnkey number off three sheets was overreach. Narrowing the scope to what I could actually estimate with confidence protected the accuracy and kept the deal moving. Beat declining the job outright or guessing at a number I couldn't defend.
The narrowed bid shipped, but the cover sheet itself miscalculated the overhead, tax and profit and printed the wrong total. Caught and fixed in the very next revision. Then a second revision wrongly left the roof out of scope, caught and fixed in the revision after that.
Narrowing a bid to protect the number is the right instinct. It doesn't make you immune to a math mistake. Check your own math like you checked your own scope.
Two real mistakes made it into successive drafts of the same bid. Both got caught and fixed in the normal course of revising the work. Not a crisis, just the work.