Note that a further complication is that some don't have a compartment but literally an indent on the tablet compartment where you're supposed to pour some prew

Note that a further complication is that some don't have a compartment but literally an indent on the tablet compartment where you're supposed to pour some prewash/detergent and it just gets incoporated into the mixture as it runs down. I suspect you can "boost" any dishwasher's prewash detergent amount by adding a bit on the door/in the bottom.