Certain things about the Sniper Rifle make it strong. (Here are a few of them, for reference.) Just like with the Fun Knobs, you want to know what makes something strong, so you can avoid backtracking. Once you move on to the polish stage, resist changing the strength of an element. (At least without admitting that you are doing it, and reflecting in the schedule.)
Don’t do half measures, if you find something that works, CRANK IT! This is especially true of power. Make everything overpowered without fear! To paraphrase The Incredibles… If everything is overpowered, nothing is.
This is the most important slide in the entire talk! It’s so easy to understand, and so difficult to stick to without wavering.
So at this point, the Flow Knobs are set, The Power Knobs are set… It’s time to flatten the rest! Eliminate the chaos and noise, put your design through the cleansing fire and get rid of all the extraneous detail. This stage takes discipline, it is the point at which you must stop adding new ideas, and start closing out the design. Luckily, if you set a determined course, you will find yourself with plenty of time at the end to add all the fine detail and polish that you want.
Assuming you are working on a game that has both single and multiplayer, you should balance for multiplayer first. Multiplayer balance is very unforgiving, live opponents will exploit any loopholes. The AI in singleplayer are a lot more flexible and malleable, so the balance doesn’t need to be as precise.