Jason.......as FCFighter indicated, everyone responds differently. Especially when factoring body types, genetics and other variables that should accompany any type of strength training regiment (in or offseason). Specifically......sport specific exercises, diet, additional supplementation, tons of stretching, and most importantly adequate rest.
For my son Silas.....continued in season weight training has worked well. However, we really transition from heavier lifts, to sets of no more than 60-70% of his max for higher reps. We’ll also only do so 2 days a week.....in contrast to a full 5-6 days during National Season.
With Silas being young for his class (literally a grade ahead of where he could be).....strength gains were essential early on to ensure he didn’t get bullied on the mat. So we began the summer before his 8th grade year and haven’t looked back. We started supplementing with 100% whey protein in 8th grade to assist recovery. That’s still a staple. He began utilizing creatine his freshman year.....but we’ve switched to a supplement called Mass Impact (Advocare) which consists of a healthy/safe mix of creatine, glutamine and other essential amino’s. His body has responded well. Eating clean and allowing at least 48hrs rest between training muscle groups has been what’s worked best for him. I’d highly recommend tons of plyometrics, agility/footwork drills, and medicine ball circuits to well round and help translate new strength towards technique.
I can assure you that there’s no “secret sauce” for wrestler development or success. A young athlete just needs to embrace the philosophy of “nobody will outwork me” and apply it to every facet of their life to become the best version of themselves possible. It sounds to me like you and your son are on that similar path. So just allow his body, as well as his mental motivation and overall drive to be the determining factor of when to push harder.....and when to ease up. It has to stay enjoyable. Because with the amount of pain a young man has to endure to become elite....the perspective of “why” has to be a daily reminder. For instance.....It’s not conditioning, it’s 3rd period preparation. It’s not about wins & losses, it’s about becoming the best “you” possible. If you train the psychological side equally as hard as the physical......the winning will take care of itself. And in doing so, you’ll build in your son the type of attributes that will make him a champion at life.....not just a champion at wrestling.
This is the dynamic that’s worked well for us. Hopefully some of this info can help you and your son inch closer towards your own mutual goals as well.