Unchanging consistency of standpoint has never been considered a virtue in great statesmen.

[Numquam enim in praestantibus in re publica gubernanda viris laudata est in una sententia perpetua permansio.]

Marcus Tullius Cicero (106-43 BC) Roman orator, statesman, philosopher

Epistulae ad Familiares [Letters to Friends], Book 1, Letter 9, sec. 21 (1.9.21), to P. Lentulus Spinther (54 BC) [tr. Shackleton Bailey (1978), # 20]
    (Source)

(Source (Latin)). Alternate translation:

Neither shall you ever finde, that wise men, and such as are expert in the affaires of the Common-wealth, praise him, that doth alwayes proceed, after one and the selfe same order.
[tr. Webbe (1620)]

In conformity to this notion, the most judicious reasoners on the great art of government, have universally condemned an inflexible perseverance in one uniform tenor of measures.
[tr. Melmoth (1753), 2.17]

Obstinately to hold to one unvarying opinion has never been accounted among the merits of those eminent men who have guided the helm of State.
[tr. Jeans (1880), 2.39]

For the persistence in the same view has never been regarded as a merit in men eminent for their guidance of the helm of state.
[tr. Shuckburgh (1899), # 152]

For never has an undeviating persistence in one opinion been reckoned as a merit in those distinguished men who have steered the ship of state.
[tr. Williams (Loeb) (1928)]

Persistence in a single view has never been regarded as a merit in political leaders.
[Common translation, e.g.]