For the person who is constantly on the move with even reasonably long presentations to make it's not always possible to recharge as you go. It's even harder when you have lots of Short Presentations and lots of traveling between presentations.

Personally I use a Inverter that plugs into a car cigarette lighter to recharge between meetings but they relies on me driving a car to begin with and that isn't always possible. Just try suggesting to a Taxi Driver to plug your device into his car and see what happens.

Even aircraft have limited recharging capabilities. Sure the bigger ones generally speaking are not a problem or the company supplied Light Aircraft as they belong to the company and can be modified for your needs but everything else is a different story particularly when you are flying Leased Aircraft not on Larger Public Routes.

Here it all Depends on what it is you do as to what is useful to you.

Col