I've been doing this the last year (ish) and my battery lasts so much longer. I suspect my data usage has been slashed as well. I recommend everyone starts using airplane mode. I just wish I could put individual apps in airplane mode so that they wouldn't be able to communicate, even when I was on wifi, unless I specifically allowed it.
You can on Android, using this: https://f-droid.org/it/packages/com.celzero.bravedns/ (it's also on Google's store: https://play.google.com/store/apps/details?id=com.celzero.br... )
Set it as a local proxy to channel all network access through it and you can selectively block any app from accessing any network, or isolate it.