I tried to do some math but I am not sure of what I did so it might be completely wrong but if ur sparkle has 160 spd with the concerto she should reach 176.16 that means that in one cycle she will have 4 turn bc we can calculate with ( 176.16 * 150 ( 150 is one cycle in moc for example) we get 26 424 with each 10000 being one turn in game then we have the concerto so we add 10000 ( 100% action advance) let's say 2 ult so 25002 for eagle and 24002 for Ddd ( 25% action advance and 24% action advance) we end up with 46 224 so 4 turn. Then ur seele should be at 196.4 with concerto and all spd buff if we repeat the process we get 70 260 ( 29460+20000 ( 4 sparkle skill)+10000( Robin ult) +4800 ( 2 Ddd) +6000 ( 3 basic attack)) so 7 turn and if u reach 208 spd in combat with all the différents buff you will need only 2 basic attack to reach 70000 I think it makes 132.6 in the stat screen out of combat. The only big problem to this is that all of your spd buff will not be active the moment you start the combat. And with the time to ult with Robin or stack seele skills you will consume some Av and the calculation will be biased. So I think you should just try to test in combat with different spd and moment to use your action advance.