Objection 1. It would seem that prudence is not in all who have grace. Prudence requires diligence, that one may foresee aright what has to be done. But many who have grace have not this diligence. Therefore not all who have grace have prudence.
Objection 2. Further, a prudent man is one who takes good counsel, as stated above (8, Objection 2; 13, Objection 3). Yet many have grace who do not take good counsel, and need to be guided by the counsel of others. Therefore not all who have grace, have prudence
Objection 3. Further, the Philosopher says (Topic. iii, 2) that "young people are not obviously prudent." Yet many young people have grace. Therefore prudence is not to be found in all who have grace.
On the contrary, No man has grace unless he be virtuous. Now no man can be virtuous without prudence, for Gregory says (Moral. ii, 46) that "the other virtues cannot be virtues at all unless they effect prudently what they desire to accomplish." Therefore all who have grace have prudence.
I answer that, The virtues must needs be connected together, so that whoever has one has all, as stated above (I-II, 65, 1). Now whoever has grace has charity, so that he must needs have all the other virtues, and hence, since prudence is a virtue, as shown above (Article 4), he must, of necessity, have prudence also.
Reply to Objection 1. Diligence is twofold: one is merely sufficient with regard to things necessary for salvation; and such diligence is given to all who have grace, whom "His unction teacheth of all things" (1 John 2:27). There is also another diligence which is more than sufficient, whereby a man is able to make provision both for himself and for others, not only in matters necessary for salvation, but also in all things relating to human life; and such diligence as this is not in all who have grace.
Reply to Objection 2. Those who require to be guided by the counsel of others, are able, if they have grace, to take counsel for themselves in this point at least, that they require the counsel of others and can discern good from evil counsel.
Reply to Objection 3. Acquired prudence is caused by the exercise of acts, wherefore "its acquisition demands experience and time" (Ethic. ii, 1), hence it cannot be in the young, neither in habit nor in act. On the other hand gratuitous prudence is caused by divine infusion. Wherefore, in children who have been baptized but have not come to the use of reason, there is prudence as to habit but not as to act, even as in idiots; whereas in those who have come to the use of reason, it is also as to act, with regard to things necessary for salvation. This by practice merits increase, until it becomes perfect, even as the other virtues. Hence the Apostle says (Hebrews 5:14) that "strong meat is for the perfect, for them who by custom have their senses exercised to the discerning of good and evil."
Source: Summa Theologica (New Advent)