They are going to try to teach you to really use your rifle. No bench. No sand bags. Most likely no bipod. Just you, the rifle, a good sling and the instruction you receive on using your body and your sling to build a good sling supported firing position.
What is a good sling supported firing position? I could say you, your rifle and your sling, again, but once you start learning what they are teaching you'll be amazed at how quickly you can get into position and put rounds on the target. You'll learn the techniques and practice them till you use them consistently. That's part of the reason you do magazine changes and you have multiple targets on 3 of the 4 stages - because it make you break your sling supported firing position to either reload or engage the next target. If you can't get back to that solid position (a key factor that is seldom spoken of on the internet is NPOA - Natural Point Of Aim) your group will not be the size you want it to be or be in the location on the target.
Above/past the Appleseed is the RBC (Rifleman's Boot Camp) that takes a week to get through and (like the Appleseed) is conducted all day regardless of the weather. I learned (naturally) way more in 6 days of shooting my M1A than I learned in a 2 day Appleseed.
Once you get that stuff they are teaching you under your belt (understanding and applying it consistently) you can lay down, sling up, put the sights on the target, close your eyes and shoot a really nice 5 shot group, without ever opening your eyes. Serious as a heart attack. A good sling supported prone firing position will control the recoil of an M1A/M14 or M1 Garand and if you understand and can get your NPOA working for you once you get on target you can close your eyes and fire and the rifle comes back to the same place. BTDT.
Yes, you'll be tired by the end of Saturday and you'll be sore Sunday morning. Take some Aleve (if your body can tolerate that medicine - I can't take it anymore do to being on coumadin) Saturday evening before you go to bed and again Sunday morning when you get up.
Take your cleaning stuff so you can clean your rifle Saturday evening. Get it cleaned/lubed so it's ready for another 200/250 rounds, or more, on Sunday. Why pay to attend, pay for gas, food/lodging and ammo only to have issues with a dirty/dry rifle?
If you go to the RWVA/Appleseed website you'll see links to a list of stuff to have/bring so you can be more organized, ready for what's going on and better able to concentrate on the techniques you're there to learn.
Good luck, have fun. Yes, if you value being able to shoot a rifle better, an Appleseed or two is worth it.
I always got a kick out of the people who make fun of it for only being 25 meters (only some Appleseeds go full distance - 400 yds.) Once you see the size of the targets, the stages of fire, the magazine changes the target changes and you've been going at it all day, you'll realize why only about 12 to 15% of the people attending will earn that rifleman's badge/patch. It ain't easy, it is fun (especially once you start realizing you are improving.)