Read emails once in your lifetime and save... lifetime

Before, I thought I was smart to not answer emails on my phone because typing on a mobile is slower than on my Mac and thus less productive.
I was still checking emails on my phone just to see what was going on and clean my inbox.

I was doing the same silly thing on my Mac: "OK I have 3 mins, just check emails to see if something important is going on and delete not relevant emails"

And then I realized I was stupid because I was reading my emails several times with this technique, which is not relevant.

Now I try to apply a new rule: read emails once.
It leads to a very binary choice:
I have time to treat emails (and I want to), I read them.
I don't have time (or I want to do something else), I don't read them.

It looks like a very limited optimization.
If you count the time you spend checking emails, you'll see it's not.
I do it, using https://www.rescuetime.com/ - consider my todo list is also in Outlook but Outlook is 20-25% of the time I spend on my Mac and Mail app is 30% of the time on my phone.