Do mortgage lenders always use actual insurance figures for final loan approval?

I would like to know if mortgage lenders always use an actual insurance premium amount, rather than an estimate when a borrower applies for the final loan. I know that during pre-approval, an estimate is mostly used. Will an estimate ever be used during the actual approval? If the actual premium will be used, how is this communicated to the lender and at what point? Does the borrower simply provide the chosen quote to the lender and then the lender plugs that into the underwriting software at time of application? Please explain. Thanks!

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