It is sad that Apple doesn't include the iPad brick with the iPhone considering the iPhone can be $1000+. It is also sad that there are so many Apple iPhone users out there that think their small iPhone charging brick is all they can use.
While I was out and about on business travels, 1. I was floored to see so many people at the airport with empty batteries on their phones BEFORE the flight, 2. Shocked to see the number of Apple users charging their phones with the small iPhone charging brick. I wanted to tell them that they could charge SO MUCH faster if they used an iPad brick or any charger with a 2.4 or greater amp output.... but I figured I'd probably scare more people than help. I use Anker charging bricks and batteries. People look at you like you're selling drugs if you offer them a charging cable.
Yes, both the 6, 6+, 6s, 6s+, 7, and 7+ will charge significantly faster with the iPad brick or any 2.0+ amp charger. Try it. Just make sure to use certified cables as well as a reputable charger company (Anker is a great one).
https://www.amazon.com/Anker-2-Port...=1495548901&sr=8-3&keywords=anker+usb+charger is what I use when travelling (used it in Germany recently).