"So based on the 20% probabilitys you have about a 10 percent chance of 1/2 recharge and 1/2 cast time. You have almost 41% chance of no benefit. THere is about a 4% chance of a 1/4 Recharge Time.
I have recently made a few 40/40 sets and wanted to examine the benefits of these sets as I have not played much with them in the past. To summarize it better for folks this may help
1/2 RT or better+++No CT Benefit=====0.2304
1/2 RT or better+++1/2 CT or better===0.1296
No RT Benefit+++++1/2 CT or better===0.2304
No RT Benefit+++++No RT Benefit=====0.4096
Total Probability=================-1.0
So you have about a 41% chance of nothing happening and 59% chance of something shortening either CT or RT or both. Or about 3 out of 5 times something good, 2 out of 5 nothing.
Although there is a beneifit you can't count on it each time. So I would not count on it for my life, but for a game or poker its a little advantage for those situations when RT and CT are important."