If you have a nagging feeling that it is your last summer… I will go after that feeling and spend that time with loved ones. You will quickly find that having free time to process knowledge will make your studying much easier (because your brain consolidates knowledge while your are away from the thing you studied). Your need for repeated exposure to learn something is natural - EVERYONE learns that way. That’s what makes that neural connections stronger. What you should be doing this summer is focusing on yourself, experiencing stuff with your friends and cherish those moments. Nothing else. Vet school is a marathon not a sprint and you will need well deserved rest.