In addition to the idea that this is the hardest game to win (almost to the FF), another thought is by this point, the remaining eight teams are usually all pretty strong. So a team wins the sweet 16 game, and only has 48 hrs to rest, rehab, and game plan for another team. Sometimes you get an "easy" scout, and sometimes you get a team like ND, with absolutely nothing to lose. Geno's reaction after the UNC game was dead on - he wasn't looking forward to HH and the ND on a mission.
Now, with the E8 game done, the team has a bit more breathing room to prep for their FF opponent. The assistants are probably already scouting SC and TCU, and then will put finishing touches on the game plan after tomorrow night. There's also an upside to only having four teams in Phoenix, that I referenced somewhere else.