In addition as a leader your best use is often to be interrupted with questions from junior engineers. This means you can never (or rarely) get into a flow where you are productive, as you are getting close someone interrupts your thought with a question.
As such if you have time to work on engineering (which you should make to stay sharp) it needs to be something unimportant to the business so that you can be late. Trying to add a new warning to your static analysis tool, checking out the latest framework to see if you should switch to it in the future - and other such things that you really want and long term are good but short term won't pay the bills.
And then making sure that they're taking action when they should take action and getting help when they should be getting help. This means they are wrong sometimes but it's better for them to be wrong sometimes and learn than to be interrupting with too many questions when they should just be doing their best.
Admittedly at this point my only direct reports are bosses themselves, but they vast majority of questions they have for me go into a shared 1:1 doc that we address monthly. Everything else they take action on and report as needed.
Days are often wasted because you do that. That is at best, I'm now up to 4 different implementations of a complex protocol (at months each to build and debug) because nobody asked a question.
sure you shouldn't just ask for every problem, but don't struggle too long when someone knows the answer.
As such if you have time to work on engineering (which you should make to stay sharp) it needs to be something unimportant to the business so that you can be late. Trying to add a new warning to your static analysis tool, checking out the latest framework to see if you should switch to it in the future - and other such things that you really want and long term are good but short term won't pay the bills.