"Out of your system" is also very relative. Technically by using half-life, it never could (Zeno/Xeno and all that). How long would it take for one last protein-bound molecule to get peed or oxidized away? How many loops around your body could it take? By math it never actually reaches zero.
So consider what it means to be "cleared". No longer detectable on a test? Which test? No more metabolic products or effects? Is it safe to take a reactive med now? Plus nearly everything has metabolites, and metabolites of those, and each of these has their own half-life, and oftentimes there's more than one path something can take; that will then depend on your personal genetics and other drugs you've taken and even what you've eaten.
Those are all reasons why there's no good answer, or at least it will depend too much, and part of the reason half-lifes are used (the other being how you measure kinetics).