English is my second language. I'm not one of those ESL speakers who will tell you they have acquired their skill without effort. There are many such people out there and I will call bullshit each and every time I hear someone say that.
I've always been very sceptical of whether I'm writing or speaking correctly and remain so. If there is the slightest doubt as to whether something I've written is incorrect or a word choice is not appropriate I'll look it up. Without consistently doing this for decades my skills would be far worse. I have a tendency to accidentally leave out words regardless of the language I'm using. That, too, makes it necessary for me to check and edit a lot. It's like making sure I haven't lost my keys by constantly making sure I have them.
I have met one or two who are somehow very gifted but, even they still put some effort in.
This is similar to the 'giving directions' example from yesterday I think as you/we know what is meant to be there so it is easy to skip in the delivery. Especially when typing fast as the fingers work behind the mind.
Interestingly, I have heard people with speech impediments like a stutter are generally above average intelligence and it is that their mouth can't keep up with their mind. I am not sure as to the accuracy of that though as it was my mother who told me.
Editing is made difficult because of the I know what it is meant to say problem also which is why it is best to have an independent proof it. Only really necessary for professional documents though.