A reaction with a very large equilibrium constant reaches equilibrium when:

1. The size of K reports where the balance point sits. 2. A reaction exhibiting a large K will reach equilibrium when most of the reactant has been converted to product. 3. A small K instead indicates the reaction achieves equilibrium after very little reactant has been converted. 4. So K is a measure of extent rather than of speed. _Source: OpenStax Chemistry 2e (CC BY 4.0), Ch 13 'Fundamental Equilibrium Concepts', sections 13.1-13.4_