When played normally and arriving from Acorn Heights
Track Type: ShroomStar 
Best Shock Spot: Beginning of section 2 (from AH) / second item set in section 3 (normal version) Whatever you do here is a gamble, although knowing how to play this track can increase your chances of doing well. Use two mushrooms for the big section 2 shortcut, then use the third to take a shortcut afterwards, and then chain your star into the 2nd set on section 3.
Arriving from Boo Cinema
Track Type: Bagging Best Shock Spot: Beginning of last lap The track itself is very short, make most of your comeback en route. There’s a big shortcut after the second item set on the final lap, but that item set is not a good spot to use the shock just because it’s so late.
Arriving from Dry Bones Burnout, Toad's Factory, or Bowser's Castle
Track Type: Bagging Best Shock Spot: Target shock pole shortcut just before last lap It’s good to know how to do the pole shortcut which you can do twice in a race. Also taking the big off road shortcut with a dodge item isn’t too bad of an idea.
Arriving from Starview Peak, Dandelion Depths, or Moo Moo Meadows
Track Type: Bagging Best Shock Spot: Chain into second item set There are shortcuts everywhere, the biggest is right after the third item set and if you get shocked before it, you do not have enough time to pull a mushroom at that set to take the shortcut. Try to take as many shortcuts as you can.