I’ve found a great little app created for OLED displays. It’s called Blackr.
You use it and the screen shows time in a tiny font showed in picture below.
This is great stuff.
Change your display time to be 30 min instead of 15 sec. Tap the screen while the little clock is on and you’re back at home screen 
Check the battery drain.
When I tested similar apps, the drain was terrible!
I will check that, thanks.
And, isn’t it better to move your wrist to watch the time?
I use it to have “ok google” active in the background so that’s my usage for this app
Hi. Coupd you please send me a link where to find this app?
Hello Øyvind. Thanks for your answer, but I could not find it on the Playstore, maybe because it is not in the french one. I finally succeed in finding the app at the following address: https://apkpure.com/blackr-oled-screen-off/com.neximolabs.blackr
Hope this may help others.
