This proceeding summarises recent studies on inclusive semi-leptonic $B$ decays, which provide key experimental inputs to ultimately increase the precision of inclusive $|V_{ub}|$ and $|V_{cb}|$ determinations using data-driven approaches. The presented analyses investigate the complete Belle data set of 711 fb$^{-1}$ of integrated luminosity, produced at the KEKB accelerator complex with a centre-of-mass energy corresponding to the $\Upsilon(4S)$ resonance of $\sqrt{s} =$ 10.58 GeV.