For a 4 digit unlock code, the device would enter them sequentially starting from 0000 and ending at 9999 [1]. Because there is a delay of 6 seconds between each attempt (on iOS 7.xx) it would take just over 16 and a half hours to try all codes.
Right now with these tools you are just playing passcode roulette to recover your device if you forgot the code and you enabled factory wipe after N tries.
Out of these retries, at least 1/N correct passcode attempts are needed, so such tools are close to useless if your care about retrieving your data with factory wipe enabled.
