From the BBC’s “An effortless way to improve your memory”:
“When trying to memorise (sic) new material, it’s easy to assume that the more work you put in, the better you will perform. Yet taking the occasional down time – to do literally nothing – may be exactly what you need. Just dim the lights, sit back, and enjoy 10-15 minutes of quiet contemplation, and you’ll find that your memory of the facts you have just learnt is far better than if you had attempted to use that moment more productively.”
And to be clear, that does not mean 10-15 minutes of quiet contemplation while engaging with your phone. Turn that off if you really want your memory to turn on.