If the battery lasts longer than 5 minutes. Sure, you could underclock the device to save battery, but what's the use of all that power in a mobile device if you can't use that power while mobile?
This is becoming a huge problem for the smartphone market. The phones are getting more and more powerful, but the batteries aren't keeping up. iPhones last about a day, maybe 2 with moderate use, and Android devices are all over the place, with some lasting for quite a while, but others lasting only a handful of hours before needing a charge.
I haven't really found a correlation between power and battery usage though: battery life hasn't really improved for a few years, but phones have gotten massively more powerful in that time. They only really need to last through the day.
This is becoming a huge problem for the smartphone market. The phones are getting more and more powerful, but the batteries aren't keeping up. iPhones last about a day, maybe 2 with moderate use, and Android devices are all over the place, with some lasting for quite a while, but others lasting only a handful of hours before needing a charge.