LDA gives the kinetic enolate of an unsymmetrical ketone mainly because

1. ALDA is a weak base so the enolates equilibrate
2. Bdiisopropylamine ($\mathrm{p}{K}_a\approx 36$) is a much weaker acid than the ketone ($\approx 20$), so deprotonation is irreversible, and the bulky base removes the more accessible $\alpha$-H faster
3. CLDA is small and reaches the most hindered $\alpha$-H easily
4. Denolates equilibrate quickly at $-78{}^{\circ }\mathrm{C}$ by proton exchange with diisopropylamine