What granularity of inventory dimensions planning runs at is controlled by the dimension group (Product, Storage, Tracking) assigned to the released product.
That said, you can't disable coverage by product dimensions (Config, size, style, color), only storage(Site, warehouse, inv. status) or tracking(batch, serial) dimensions.
Also, you don't have to create an item coverage record for each configuration, only the ones you want to keep some minimum inventory on hand for in a specific site / warehouse. If there's no item coverage record, planning will plan based on the coverage group on the released product -> plan fasttab, and if nothing there, using the general coverage group defined on the master planning parameters.
