Think you missed the fact that you still need fast speed to actually deliver the attack. FTG only gets you to the target, your own physical speed needs to be fast enough to hit the opponent. Edo Minato isn't as fast as Alive Minato since he's not at full power. Madara even said Tobirama who was once held the fastest of their time is no match because he can't use his full power. Madara was nerfed, he has the power to kill both Sasuke and Naruto with 1 eye alone. Let's use jutsus we know Madara knows: make 25 clones which each uses limbo that attacks Sasuke as the clones attack Naruto. Madara will use Susanoo (which he did not use once after becoming the Juubi Jin, it will be stronger than Sasuke's), Deva path (didn't use as JJ), Katon (didn't use JJ), pretha path (didn't absorb any jutsu), ect...
Sasuke's Shunshin is slower than A, Tobirama, and Minato since they have higher chakra reserve which allows them to go faster. Sasuke doesn't just look and boom. He has to use the proper chakra and switch with something that he sees. He also has to rest it after using it after certain amount of use. He couldn't use it for a whole chapter after using it on Madara. Also Sasuke only got Madara because Madara didn't care to block or else he would have used Deva path or Susanoo. He wanted his other Rinnegan to complete his goal is all.