First of all, I'm talking about the 3x3x3 cube. I use Fridrich F2l, OLL, and PLL. I define lucky as skipping 1+ step/s (each C.E. pair counts as one step). When I say chances, I am trying to say probablity. If you have any other questions about the question..ha..feel free to ask. Thanks again.
Each step may be defined mathematically by the number of positions it holds. If you skip that step divide the total number of possibilites by the number of that step.
Your question at first was not so specific to a particular method and gets a slightly different answer. It's impossible to calculate the odds because the more you know and can do, the fewer occurances can be considered lucky.
Consider that my method contains the possibity of knowing how to skip steps. You can skip the Last Level completely and it would not be lucky.