I probably spend around 80% of my time coding in a senior role with around 12 years experience. I think it depends highly on where and what you work on.
If you have 8-10 engineers you’re supervising and are the person interfacing with management, I don’t think it’s unreasonable to spend half your time coordinating, teaching, and planning.
So scale down the expected SDE 1 quotas (~50% coding), and you get around 25-30% coding time.
I think a lot of people confuse being an experienced career engineer with being a technical lead; that’s the real jump from SDE 2 to SDE 3.
I think I'd get a lot less than 25-30% coding time while managing 8-10 people (and also depending on what you're doing while "supervising", if there's a dedicated project/product manager in addition to you, how senior are the other engineers, etc)! In fact at that point I think I'd be managing too many people ("ideally" 1 lead/manager isn't managing more than 5 ICs).
My experience of Big Co is that you have both a manager (HR and business sense) and a supervising/lead engineer (SDE 3) for a product.
I don’t think I explained that well — but a 3:3:1 to 5:5:1 SDE 1:2:3 mix is fairly standard across industry. (Again, with an SDM doing the managing.)
I used the word “supervising” because I wanted to distinguish that technical leadership from managing, but didn’t explain enough. Sorry for the confusion.