The 15 minute reset works but you get different results if you do it yourself or have the settings cleared by the dealer before doing it.
If the you do it on your own, the ECU goes into “Learn” mode which can take up to 500 miles before finally settling in. This is probably why some people have to do frequent resets – the bike runs pretty well with at the reset settings, but as the ECU starts making adjustments performance deteriorates. This is also why you should have a fully run-in ECU before trying to tune the bike with a Power Commander or a TuneBoy. This also jibes with what 9nine0 posted.
Now, if a dealer clears the ECU and then does the reset, the ECU goes into “Quick Learn” mode and it doesn’t take nearly as long for the ECU to settle into it’s final ‘learned’ settings. Not sure how long it takes though.
The above is what I have gathered from talking to my KTM tech, my own experiments and lots of reading over on the Super Duke boards, so take it FWIW