Is there a best practice recommendation for scanning individual ingredients vs. the final product when there is nurse admixture at the bedside?

An example: nurse has to mix an IV antibiotic prior to administration. When performing the scan, is your system process to have each ingredient scanned, or is a final product label/barcode provided to scan?

My gut feeling is that best practice would be to scan individual ingredients. There is always the possibility of a wrong product selection prior to the final admixture.