Leadership has always been about decision making and dealing with complexity. One thing constant with leadership in any decent size organization is that every now and then you will be presented with a situation with no precedent. You will have to think thru long term implications of your decision without taking forever to make that decision.

Especially events of past few years forced us to make decisions on how we work and make decisions frequently for which there was no precedent in past.

In my opinion, having a good reading habit is number one skill that helps build that decision making muscle. And second one is good writing. With amount of information deluge coming at us from all directions, and decreasing attention spans, good reading and writing skills are needed as much, if not more , than time management, delegation and speaking skills in a leader.

I believe a well built reading muscle can help you pick up and jump start on all the other skills. In this day and age of tiktok, audioooks, not to mentions yotube, you would think that reading  & writing is not that important. In fact it is the other way round. 

Decision making requires deep thinking and clear mind. Nothing comes even close to writing and reading when it comes to think deeply, do trade-offs and make decisions. 

Audiobooks, youtube etc may be good for learning high level concepts or how to fix your appliance.  May be for improving  your golf stroke but when it comes to deep thinking and decision making, these are not enough. These  lack the quite, stillness and focus  that is needed for mind to think deeply.