The first mass product import I was involved in happened in a matter of days. It required intensive reconciliation. I got involved once the import had taken place. My challenge was reconciling product setup between ERP systems in order to get inventory decrementing properly. I diagnosed the problem, created the solution for fixing it, and implemented that solution. Beyond finding and correcting mass systematic errors in NetSuite, I have set up thousands of products and integrated those products across eCommerce and warehouse management systems.
I am intimately familiar with product setup in Magento. We first met when I was in charge of setting up conditions and rules for eCommerce promotions. Magento and I really got serious when I took over product setup. Thousands of configurable, bundled, simple, and group products later, my relationship with Magento hasn't been without its battles, but I'm comfortable saying I know the Magento platform inside and out.