Determination vs spell speed and resetting stats at level 50 questions

[DreamWeaver]

To Zaft:
just want to gain additional insight!!

Fact 1: Any equipment set (DET,SS,Crit,PIE) can be used to clear all content of FF14 ARR currently.
Fact 2: 99% of all encounters in FF14 ARR is scripted

Debatable 1 : Spell speed helps you to react faster if you are caught off guard.
Debatable 2 : DET provides noticeable impact to your healing value.

Now, although every encounter IS scripted, but for fresh people who just started tackling these encounters, won't SS helps more than DET, since they do not know the scripted events, and thus require to react to them.

OK, now the same fella has gone through the fight numerous times, and is now able to clear it comfortably and he knows all the scripted skills/events, thus he is able to pre-cast in anticipation, thus SS is useless for him now. However, as seen above (Fact 1), although SS is useless to him now, he will still be able to clear it, switching to DET may provide more benefits now, but end result is the same : Clearing the encounter.

Thus this is my key point, if SS helps when you are learning an encounter while DET does not (My Opinion!!), and both DET(optimum) and SS is viable once you have learnt the encounter, does this not mean SS is better than DET?

Thank you and anybody who want to provide input in advance for your insight!!