Hi Ebo, my pleasure!

One thing I will say is the importance of writing skills went up with levels. Poor writing skills weren't career-limiting for SDE-I or SDE-II or even Senior Engineers. They became a more serious obstacle to get things done as Principal. And they became career limiting at Director level or higher.

I don't think Amazon would let somebody go just for poor writing skills, but poor writing skills at higher levels would be a blocker for that person to Earn Trust from others, which in turn would be a blocker for them getting things done thru others - which in turn could end up getting them in a performance improvement plan. At the lower levels you can get things done by writing code yourself; at the higher levels you're getting things done thru others so writing is more important.

There were good training (courses, talks, etc). But a lot of that was done thru trial-and-error too. I wrote a 6-pager that I took to CEO, but that was only after having written dozens of other 6-pagers, and only after having done dozens of reviews with others. The final 6-pager that I presented to Andy Jassy didn't look anything like the first version I wrote!

Happy New Year!