Step 4 contradicts basic physics. What you are doing wrong is that you are confusing power with energy. If you lift the weight slowly you need less power becaus

Step 4 contradicts basic physics. What you are doing wrong is that you are confusing power with energy. If you lift the weight slowly you need less power because for the same work (= energy) done you can do it in twice the time. But using less power over longer periods of time will result in the same energy consumption.