Of course our ipad air batteries were made to fully charge. However it is good over time to charge your battery to 75 , 80%. For all those times it will receive a 100% charge is fine of course.
I always play catch up with my charging.
It's better to put a 30% charge on it every day to bring it up to full ( which in my case is 80% ) instead of a full drain and a full charge each time it's needed.
I hope I can find the source of the info. It was a reliable source I remember.
Another thing which I feel we all know is controlling heat in any way it relates to the device. The ipad 3 had the big issue with heat yet I never felt any heat on my palm when checking. I'm thinking maybe because I used these tips.
Hope to find the source. Last seen it around 15 months ago.