By creating a dictionary containing strings of fixed length of 24 characters based alphanumeric (1234567890abcdefghijklmnopqrstuvwxyz)

es.: ad78 u7g5 m0m1 jqwe bb61 naq2

given the enormity of the possible combinations would give 36 ^ 24 as the number of strings 22,452,257,707,354,600,000,000,000,000,000,000,000

By a dictionary attack to 10,000 keys per second with the number of keys you want about 71,195,642,146,608,800,000,000,000
years, without considering that contain a dictionary of that length that is 445.729.734.805.631 Yottabytes or 501,847,066,894,648,000,000,000,000,000 Gigabytes.

Done this premise my question is:
Who uses WPA keys as described above and a dictionary attack would be folly;
There is another method for discovering a key WPA? Or this connection it can define safe to 99.9%?