I find it odd that you say that mappings have to be set each time. The 'mandatory fields' in the example given by Quickbooks Online don't have to be selected each time, but the exceptions is that ItemAmount has to be selected each time, as well as Exclusive/Inclusive of tax and Invoice Date format. Surely Intuit can make a default setting so that we can always make sure our csv file matches the default.  I have uploaded a PNG File to illustrate. It really is an error prone time waste each week.