Android is full of wonderful little touches here and there that we either forget or have never come across in the first place. One of these is the very neat time-saving ability to double tap the Recents button to switch to your previous app. The functionality was added way back in 2016 with Android N, and has been saving us time for two years now. If you didn't know about it though, and many of you did not, this will be your new favorite thing.
Double tapping Recents / Overview works a little bit like Alt-Tab on a computer. It switches to the previous app you had open on Android, then double tap again and you're back to your first app. I use it daily when I'm taking notes while editing Android Police posts: going back and forth from Chrome to Google Docs would be a chore otherwise. On phones, I find it's a lot better than multi-window since it gives me the full screen estate of the two apps with an easy way to switch between them. On tablets, I still prefer multi-window if I'm going to be using two apps simultaneously for a while.
If you've never given it a go, try it now. It's quite possibly our favorite Android shortcut. But maybe you shouldn't get used to it a lot, at least if the screenshots from Android's gesture navigation are to be believed.