One nice feature of Apple Pay Suica is that once set up it’s just a regular Suica transit card. You can recharge Apple Pay Suica with cash, and you can use it without a network connection: Apple Pay Suica works perfectly in Airplane Mode.
This is handy for long train trips when you want to conserve battery power. The one thing you don’t want to do is run out of battery power before going through the ticket gate of your final station. With Airplane Mode on you’ll have plenty of juice for your entire trip and can still use Apple Pay.