A good friend of mine is a research economist who studies the labor market. It turns out that the factors governing a person's satisfaction in a job are similar to the factors that govern a person's satisfaction in a relationship. Simply put--a rational person would leave a job when the costs are greater than the rewards. People do this all the time. Likewise, a rational person should search for a relationship that will have more rewards than costs.
Following this logic, there are a few consequences:
0) one can't assume people are always rational
1) there is a cost to switching relationships, so it pays to get it right as soon as possible
2) you are unlikely to enter a relationship with someone you have never met...therefore in order to find the best relationship, you should meet as many people as possible, or be lucky
3) if rewards >> costs, maybe it is worth having a job/relationship for a longer time, versus holding out for somethign that is slightly more optimal
I came across this website (below) when I was Googling for interesting info. It will calculate, from a statistical distribution based on census data, how many people you should meet to ensure you find ONE person who simultaneously satisfies all your criteria, in your geographical area (at least in the USA) [I have no affiliation with the site, just found it interesting]
http://www.solvedating.com/soulmatecalculator.asp
(Note, most of these distributions are normalized about the mean, so picking 10% is equivalent to picking 90%)
Haha...also...it should go without saying that just because you might be able to meet a million people and FIND your soulmate...that doesn't ensure you're able to attract them and close the deal
The easiest way to maximize your search space is to give internet dating a try. Everyone I know who has given it an honest go has learned something important about themselves and what/who they want; five have met a husband/wife, several are still dating, and one even met a cool gal who later set me up with her best friend...