The mid of it gets the best combos in most situations.
First part of hit behind Pit: Either you need to turnaround followup which can be jumped out at higher percents, alternatively jump while holding backwards and up-air, but with good DI you will need great arrow usage to extend the combo further.
At high percents you can follow up with kill moves, like arrowing->(up-air as often as intended->)up-b or bair when you are close to the edge.
Middle part: Often sets up for the up-air juggles, up-air is the ideal mid-combo move because it racks up damage while you keep your ability to combo, in contrast to fair where you need to move to combo and it is easier getting out. Essentially, if you up-air juggle, you can still start fair carrying your opponent offstage, while you don't get the opportunity to start up-airs after fairing that often.
Last part: Great offstage because it is actually a spike, even if it is the weakest spike in the game. If you hit a grounded opponent it sends diagonal so when he DIs away you can fair at low %s or use a few arrows into aerials, however the combo will be not as big in average as with the middle part.
Be aware there is an exception if you fight characters with bad recoveries, great anti-techchase tools and many platforms to tech on. In this case going for the fair chain without up-airing that much before is the better choice which would make the last part great.
