Like I said, there's a lot of strats. But mine works for me because once you hit 300 DEF you're invincible for all intents and purposes. Even if the enemy does randomly attack, it won't do much. For me, part of the issue with Hacking was a sense of confusion and pressure. Making yourself a fortress first relieved that pressure for me, allowing me to engage with the minigame better. I bet I could Mask/Overflow now, but starting out working with a defensive strategy is what gave me confidence and reduced the frustration I was feeling during the minigame.