Eric Hoffer insisted that everyone needed time to think while your body was otherwise occupied. He famously wrote The True Believer, published in 1951, while working his job as a longshoreman on the docks of San Francisco.
Unloading ships, mowing the lawn, or walking, whatever you do, you need quiet to hear yourself think. Time to digest whatever you've ingested in your intellectual diet, combine it with news from the day, and distill new knowledge or wisdom, concrete ideas that you can use to guide your choices and actions.
However, the age of podcasts and bluetooth headphones has made it easier than ever to listen to something while you do otherwise repetitive work. Having many episodes queued up to listen to makes it tempting to listen to each one at 1.5 or 2x speed, not thinking what the effects are of giving each moment 2/3rds or 1/2 the normal amount of attention.
I've fallen into both traps.
I used to think that I had accomplished the goal of listening to a podcast if I'd understood each word of it, and I got quite good at listening to many things at double speed. Only recently have I come to realize that it's the moments in between, when the speaker is pausing and your own mind has room to think and process that the work is actually being done. That you consider what they're saying, and knit it together with your existing web of knowledge so that it is attached and doesn't float out of your consciousness with the next interruption.
Working from home this year due to the COVID-19 pandemic took about an hour of time spent in the car four days a week out of my listening time. At first I just tried to listen to more faster. I started giving myself permission to delete episodes unlistened to. (The over-produced, hour-long public-radio-ish podcasts were often the first ones to go, because they seemed to meander about a point but never be willing to state anything clearly. I kept them in my feed because I think a balanced intellectual diet is important, but I just couldn't justify the time they took to say so little.)
Now, I'm coming to realize that it is also important to not fill every moment of quiet time. Important to have time to hear yourself think.
In fact, even this post is the result of that, twice over. First because the idea emerged fully-formed from my unconscious when I was taking some time to quietly peruse the news as I do once a day from my phone, a much less intellectually demanding task than listening to a podcast at 1.5x. But then I was distracted by something and later could only remember that I meant to write a blog post about something or another. It wasn't until I was later aimlessly noodling on a guitar in my study that this entire piece sprung back to mind, essentially fully written.
I could have easily filled that time with podcasts while I busily checked another thing off on my to-do list. But I'm getting fairly tired of how no amount of podcast-completing and to-do-list-item-checking-off I do, it seems like the day has flown by without doing anything at all.
The answer seems to be to create, and not just consume. Write something, have a meaningful conversation with a friend, record a podcast, practice a skill.
And make sure to leave some time left over to hear yourself think.