Open Question: How do I hit my stocking time goal?

I work the Flow Team at Target, and my manager says I'm over an hour slow. Considering my goal time is 1:50, it seems impossible to be that slow when I am working at a steady pace and minimizing my steps. On the sheet she gives me it says 319 under "Stock Eaches Total" (is that boxes?), and 1:50 for my stock goal. If those are boxes, how am I supposed to do one every 20 seconds? The steps are to get all of the boxes off the pallet and into the proper lane, open the boxes and stock the shelves, and collapse each box and put it in a cart you have with you when the items are out. Just the walking time alone per box can be well over 20 seconds. I have to walk from the pallet to the lane, back to the pallet to throw the next box, and then back to the lane eventually to unpack it. If the place is a little over 6 seconds away from the pallet I have no time to even unpack it, let alone collapse it. I don't even wait for help with team lifts or anything, and I'm moving as fast as I can without slicing my hand open with the box cutter. What am I doing wrong?