Definitely try to validate as many courses as possible. You achieve two things. One, you get invaluable time sitting in an air-conditioned room; don’t underestimate how good that feels in the middle of plebe summer. Two, you give yourself options; doesn’t necessarily mean you have to act on every validation you achieve.
Once you have your results, try to strike a balance. On one hand, you can create great flexibility in your schedule as the years progress. On the other hand, you can create great stress for yourself by taking even harder courses in plebe year.
An example: DD validated Calculus 1, Chemistry 1 and English 1. So fall semester of plebe year — arguably the most stressful semester of a midshipman’s career — she tackled a harder-than-normal course load. Calculus 2 was brutal. She leapfrogged Chemistry 2 and went to Modern Chemistry — a course for majors — which almost put her in a straitjacket. English 2 was no walk in the park either. It all worked out in the end — she now has space to take a minor — but it made plebe year even harder than it had to be.