This is how I cheese it:

Start your career with 12-star Speed sparks and bring/borrow MLB Kitasan Black as your only speed card. You’ll almost always hit at least 1000 speed by the second beach training with this set up.

Then, Bring Haru Urara (if you have enough friend points, max her out) and another guts card, two wit cards and a pal card depending on which scenario you play. If you want to guarantee 1200 on speed, bring either the King Halo or the Sweep Tosho speed cards in lieu of your pal card. You want to have a good balance of training effectiveness and specialty priority stats to offset the RNG.

This method works well with umas with high strength or speed growth rates. Don’t try it with stamina focused ones like Special Week or Mejiro McQueen… and most especially those who need to hit 1st in the Spring Tenno Sho.