In an aldol reaction, a common procedure is to use hydroxide or alkoxide as base in water or alcohol. In either case, the pKa of acetone, for example, is about 20, so the equilibrium favors the ketone. After formation of an enolate, it can become protonated again. This would appear to be no reaction because the starting material is recovered. Because the pKa of a CH2- and CH3-group are close, even though the CH3 will form an enolate faster, it can become protonated by the solvent to reform ketone and hydroxide or alkoxide. Therefore it is possible for the reaction to form many enolates which return to ketone before any aldol reaction occurs.
For most reactions, the kinetic (the one that forms the fastest) and the thermodynamic product (the one that is the most stable), are the same. In this instance, the kinetic intermediate does not become converted to the product. The overall product of this reaction comes from the thermodynamic enolate. That was the original question I was trying to answer.