Pretty simple steps to complete your Inning Programs in diamond dynasty quick, requires 2 controllers (you cannot get banned for doing this)

1. Go into exhibition mode
2. Put your account you want to get the XP as the away team and the 2nd controller as the home team
3. Load into the game and make sure you have the correct settings applied like in the video (if you forget you can do it in game as well)
4. Simply walk the batter (your team) and go to about 250-275 runs. You can just press start and confirm exit.
5. You will load back into the main menu, it'll show you got the XP but it will not actually apply until you either quit the game and load it up (3 times you have to do this) or you can play 2 moments challenges in diamond dynasty. I just do the moments I feel like it's easier.
6. Rinse and repeat until you get 650k XP.

Watch the video if you have trouble following the steps but it is quite easy. A rubber band on the left bumper of the controller you're using to walk your main account with really does come in handy since then you only have to press B + A or O / X depending on your console.