You should usually get at least two or three contractor quotes when the project is material, the scope is unclear, or the first price looks unusually high or low for your area.
When three quotes help the most
Three quotes are especially useful for projects such as roof replacement, basement waterproofing, and fire damage restoration because scope packaging varies so much from one contractor to another.
When two quotes may be enough
If you already have a highly detailed quote and a clean local baseline from the quote checker, two strong estimates may be enough to validate the range. The real goal is not collecting numbers forever. The goal is understanding scope.
How to make the quotes comparable
Ask each contractor to bid the same scope assumptions where possible. Then use itemized comparisons and the quote inclusion checklist to line the bids up more cleanly.