adjust gear ratio according to top speed or to cell count?

[mistercrash]

I have lipos to run my BL ERevo in 4S, 5S and 6S. The racing season starts soon and I'm going to race this truck. I still don't know which cell count I will prefer for racing, track time will determine that. What I'm wondering about is should I set a top speed and gear up or down to achieve that same top speed no matter what cell count I use or should I gear according to the cell count so that motor, ESC and lipo temperatures stay safe and have the top speed change depending on what cell count I'm using?

Thanks
Ray