Why does everyone assume he's lying? Some people don't study, period, except right before a test. If it's an exam week, they might only have a few hours to do their 'non-problem-set' studying.
Not everyone actually does the textbook reading, beyond referencing back when they get stuck during problem sets.
Of course, doing well on tests =/= doing well in the course, especially if it has a lot of projects, lab reports, papers, etc...nor does it imply long term retention. So, yeah, as someone who can generally do well on a test despite never having done any reading for the class, I'd say that my grasp of the material a few years down the line is suffering for it. There's definitely a trade-off; natural intuition paired with decent recall might get you through a test when you've absorbed all of the material through lecture recently, and when you crammed for the past 3-4 hours...but it doesn't do the work of cementing it in long term quite as well. Some people might not have that problem, I don't know. I certainly do.
Personally, you can look at my transcript and see which courses relied mainly on testing and which ones required you to put the work in and manage your time. I'm very good at one, not so much at the other. Would I trade? Nah...I'm in the process of training myself to have good study habits, and I feel that I can end up with both. I don't think that I would feel as capable of training the other way, though.
I guess what I'd say is that, while some people can just 'get' it, the habits you develop, while more time consuming, are probably more valuable in the long run, especially in med school. Your grades are fine and you're still looking to improve; I think you'll be OK 😉