The moment has come, to examine the question that we had posed:

"Why doesn't the Holy Spirit speak in the hearts of all baptized individuals?"

Also:

"Why does the Holy Spirit speak to some very much after their Baptism, and to others from the beginning?"

According to the words of the Apostle Paul, each baptized Christian must have the Holy Spirit in his heart, Who will co-testify together with his own spirit about his adoption:

"...For you have not received a spirit of servitude once again, in fear; rather, you have received the Spirit of adoption, in Whom we cry out 'Abba, the Father'..."    [Romans  8:15]    (also compare Galatians 3:26-29)

In the Epistle to Galatians, however, he provides us with the reason that certain sons do not have the co-testifying of the Holy Spirit about their adoption:

"....during the time that the heir is an infant, he does not differ from a servant, albeit being the master of all; rather, he is under guardians and stewards, up until the time appointed by the father. Likewise, we also - when we were infants - were subjugated to the elements of the world; however when the fullness of time had come, God sent forth His Son, born of a woman, born under the Law, in order to redeem those who were under the Law, so that we might savour the adoption. Because you are sons, God sent forth the Spirit of His Son into your hearts, which cries out 'Abba, the Father'.  So that he is no longer a servant, but a son; and if he is a son, then he is also an inheritor of God, through Christ..."   [Galatians 4:1-7]

So, we can see here the reason that certain Christians take longer to receive the lowest of the charismas (gifts), the prayer of the heart:  If a baptized Christian has not yet been cleansed of his worldly passions (even though God has cleansed him of his sins during Baptism), he is still in a sinful state of the heart. Thus, even though God has put a person's "old self" to death with Baptism, each time that person sins, He will resurrect him again.  God is therefore treating him like an infant. Inasmuch as this person still has far to go until he reaches "the measure of stature of the fullness of Christ..." (Ephesians 4:13-14), he is not yet perfected. So, just as a father does not consider his little son worthy as yet, in order to entrust the family inheritance to him and treats him like a servant, similarly, God does not entrust His gifts to someone who is still "spiritually an infant".

He too is a son, but is not yet worthy of undertaking the responsibilities that the charismas of the Holy Spirit entail.  Only when his heart is cleansed of all worldly elements will he be a "perfect man", ready to handle the gifts of the Father.