I've heard a few people say the same, but personally I kind of begrudge doing that and using two different devices. If people are paying a lot of money every month to have a smartphone, surely it should be up to the manufacturers to make sure that the device is fit for purpose, and we shouldn't have to walk around with two phones. The more people try and find a way around saving battery life by doing things like this, even though in the short term it's to our benefit, in the long term it's making the manufacturers think that they can carry on making devices with poor battery life and it's not that important when really it should be the first thing that they address.
@Log Ini now that Power Banks are available perhaps the need of keeping two phones will not be necessary but then one will have to keep a charged power bank
Nowadays, people are using a powercharge to make sure that they don't run out of battery charge. I usually switch off my phone during the night to make sure that my battery lasts longer. I have the advantage of the fact that my phone has a small screen which means that my battery lasts much longer. I also have two batteries so that when one is charging, I use the other one since I am a heavy browser.