Cast Time and Cooldown Calculations

I actually knew about this a long time ago, I just forgot about it since it's just that pointless to know.

(Base time) * ((100 - (percentile value))/100)^(how many stacks there are)

Or something along the lines of that.

(Formula is a bit messy, doubt you'll be able to understand it)

Anyways, what this means is that the calculation is multiplied and not a stacked value. What this also means is that the effects of reducing cast/cooldown times are a lot less effective than they appear.

(Note: Examples are fictitious and doesn't reflect real in game equipment)

Example:

Agi cast time is 1 second
Armour decreases cast time by 10%

So instead of decreasing 10% OF 1 second (which results in 0.9 second) we plug in my messy formula to get:

1 * ((100 - 10)/100)
1 * (0.9) = 0.9

The result is the same, but when we continue to add different reductions such as...

Example:

Agi cast is 1 second
Armour decreases cast time by 10%
Crystal decreases cast time by 10%

Now normally you would think that it would be 1 second minus 20% (result is 0.8 second), that is not the case. You have to plug in the formula.

1 * ((100 - 10)/100) * ((100 - 10)/100)
1 * (0.9) * (0.9) = 0.81

In other words, 10% of 10% of 1 second. However, the reason why I made the formula format like this is because of what happens when you add stacks to it.

Example:

Agi cast is 1 second
Armour decreases cast time by 10%
Crystal decreases cast time by 10% (2)

Again, you would think it would be 30% of 1 second (0.7 seconds) but that is not the case and where the formula gets a but more math intensive.

1 * ((100 - 10)/100) * ((100 - 10)/100)^2
1 * (0.9) * (0.9)^2
1 * (0.9) * (0.81) = 0.729

Again, difference is minscule.

Increased Cast/Cooldown Times

Same formula applies, just add the percentage instead of subtracting.

Some Irregularities

Now I just want to make sure because of how the nature of this post is that I mostly took the tests from somewhere else and went from there. Including the fact of how lazy I am to test these things. I just wanted to make sure of some minor aspects clear.

Stacking Percentages

I am unaware of how specific it needs to be for the percentages to stack. For example, if the Top armour and Bottom armour both decrease cast time, do they stack? Or in different brackets?

Same issues with crystals. If they are the same crystal they stack (for example tarots) but what if they are two separate crystals?

Conclusion

So although cast/cooldown times are a lot more complicated than they seem, my question is, "Does anyone even care about it?"