Like it of hate it, this is what we have for armor crafting so all we can do is learn to live with it. Part of this involves around "managing expectations" (sorry for the use of this catch-phrase to those of you who are sick of it). Obviously, very few of us went in on our first attempt and crafted up the exact armor we wanted. As I will illustrate below, the chances of doing that are rather low.
I wanted to get a rough idea as to how many runs it would take to get the armor I wanted. Obviously, there is never a 100% chance you will get what you want in a random system, however you can determine the statistical likelyhood of obtaining the desired result if you know the number of possible outcomes.
Each of the tiers have over 20 possible upgrades, from what I have been able to discern from the various posts on the forums. It looks like tier III has at least 30 possible upgrades, and so far I cound 22 for tier II and 26 for tier I. I suspect the tier I and II numbers are a bit low but, for now I will use these numbers as the difference is not hugely material to the number or required runs.
With these numbers, the chances of getting what you want each time are (assuming there is only 1 outcome for each tier that you will find acceptable):
tier I: 1/26 or 3.8%
tier II: 1/22 or 4.5%
tier III: 1/30 or 3.3%
The chance of all 3 of these working out for you on your first attempt are very low:
3.8% * 4.5%* * 3.3% = 0.006%...
...not a bet any rational person would take, though it suggests that 1 out of every 16,667 people will get what they want the first time (probably that annoying person on the forums who brags about their luck... of course they are not lucky, they are just a statistic).
fortunately for us the 3 tiers upgrade independantly of each other, so our odds of getting what we want on subsequent upgrades increase markedly. I usually consider the 80% success rate as a number by which i can reasonably succeed. In order to have a 80% chance of the desired outcome it would take:
tier I: 41 attempts
tier II: 35 attempts
tier III: 48 attempts
of course this means, that 2 out of every 10 people will not have what they want after the above numbers of runs. These people are usually the loudest in their complaints, so I expect a fair bit of complaining about the number of runs required.
Also, the numbers required for a 99% success rate are:
tier I: 117 attempts
tier II: 99 attempts
tier III: 137 attempts
which basically means that 1 out of every 100 people will upgrade their armor over 100 times, and still not have what they want. These people will be the ones who post on the forums, thinking the devs are out to get them.
On a point forward basis though, these numbers are not useful for setting expectations. your odds of achieving success on your next try are always the same as your odds of succeeding on your first try... just something to keep in mind.
Oh, and other people like to know when their odds will be 50/50 as a bench mark. Those numbers are:
tier I: 18 attempts
tier II: 15 attempts
tier III: 21 attempts