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It took me about a month at to sleep off my debt.I am pretty sure you didn't "sleep off your debt". Sleep debt is something you easily recover right away, just by sleeping until you wake naturally.
What you did was to shift your circadian phase. The circadian phase is usually measured by the nadir point of the core body temperature rhythm [1] (apparently the better measurement is of the "endogenous melatonin rhythm", but it's easier to talk about core body temperature).
Apparently you can force the nadir point forward, but it's relatively hard to move it backwards. You move it forward by delaying sleep, thus accumulating sleep debt that causes you to get up increasignly later. To move it backwards you have to curtail your sleep, thus accumulating sleep debt which needs to be paid at some point.
About your solution: As a fellow night owl, if I just set my sleep cycle free, at it were, then my wakeup time quickly shifts to around 16-17:00, and I sleep 9-10 hours per night. So while your recipe works for you, it's not for everyone.
[1] http://www.cmse.ch/pdf/colloque_14_octobre/6_approche%20trou...