As students, we've probably all done it--burned that midnight oil trying to somehow shove data through our eyeballs and into our brains. And when the pressure is on, we still can do it as professionals, too. The neuroscientific research, however, says that cramming is not the way to go if you need to learn something really important.
As Dr. Eric Haseltine writes in the November 2018 issue of Psychology Today, there's a cap on how many new connections (synapses) your brain can make for a memory in a set period of time. Just as it takes construction workers time to lay a foundation and install everything you need in a house, it takes your brain time to synthesize the proteins necessary to create the synapses that will help you. So not surprisingly, studies have verified that this synaptic development is superior when you space out your learning over time, compared to if you try to cram.
Now, I recognize that there are going to be times as a leader when the world just doesn't give you the ideal amount of time to put information into your memory. But when push comes to shove, the wickedly fast whims of the market aren't going to change biological truth. No matter how badly you want to remember everything by tomorrow's meeting, you can't ask your brain's construction workers to build you a house by morning. You can help them out and maybe up their deadline a little with some of the other tricks Haseltine talks about--for example, rhyming with ingrained memories--but once the synthesis is full steam ahead, it's full steam ahead.
So be realistic and a little more forgiving to yourself. If you know a project is critical, avoid the temptation to rush. Review the information you need in different ways over time to make sure you really understand even the details and can apply the concepts well. Instead of agreeing to a pace your brain can't handle because you're afraid you won't impress, make it positive. Communicate your desire to develop an expertise that's going to work for the benefit of the company not just for the immediate project, but for the long-term, wider scale. Give updates to show your learning progress, and make scheduling more collaborative. Most people will slow down if you ask if the benefit of the delay is clear, and you'll avoid unnecessary stress that could interfere with memory encoding.
Experts compare the brain to a supercomputer for a reason. But its capabilities aren't infinite. They're bound by basic principles of physics and chemistry, and these don't go away just because Joe/Jane from Big Investment want answers from you now. Push up to the limit as hard as you can, but give that construction crew of yours what it needs to do its job, including minutes on the clock.