This is a variable that can make or break an Ambitious Card Routine. What do you think is the right amount of phases before it gets redundant?
What sort of question is that? As long as it is interesting and varied.
If you do an ACR with 8 moves, and all 8 are the card going from middle to top, it will be boring. But if the first time it appears on the top, the second time on the buttom, third time in your pocket, fourth time with a shapeshifter color change, fifth time under the box, sixth time inside the box, seventh time it jumps out from the packet and in the eighth it dissapears completely from the deck... Well, it will be interesting, cause you can surprise your audience every single time.
Watch Derren Brown do a very long three cards routine in the Devil's Picturebook... The same three cards keep appearing again and again, but each time it is done very uniquely, and the routine isn't boring even though it's very long.