Please, consider the following...
“No one can come to Me unless the Father who sent Me draws him; and I will raise him up on the last day. “It is written in the prophets, ‘and they shall be taught of God’ Everyone who has heard and learned from the Father, comes to Me." (John 6:44-45 NASB)
“For which one of you, when he wants to build a tower, does not first sit down and calculate the cost to see if he has enough to complete it? Otherwise, when he has laid a foundation and is not able to finish, all who observe it begin to ridicule him, saying, ‘This man began to build and was not able to finish.’ Or what king, when he sets out to meet another king in battle, will not first sit down and consider whether he is strong enough with ten thousand men to encounter the one coming against him with twenty thousand? Or else, while the other is still far away, he sends a delegation and asks for terms of peace. So then, none of you can be My disciple who does not give up all his own possessions." (Luke 14:28-33 NASB)
"Now the parable is this: the seed is the word of God. Those beside the road are those who have heard; then the devil comes and takes away the word from their heart, so that they will not believe and be saved. Those on the rocky soil are those who, when they hear, receive the word with joy; and these have no firm root; they believe for a while, and in time of temptation fall away. The seed which fell among the thorns, these are the ones who have heard, and as they go on their way they are choked with worries and riches and pleasures of this life, and bring no fruit to maturity. But the seed in the good soil, these are the ones who have heard the word in an honest and good heart, and hold it fast, and bear fruit with perseverance." (Luke 8:11-15 NASB)
“But what do you think? A man had two sons, and he came to the first and said, ‘Son, go work today in the vineyard.’ And he answered, ‘I will not’; but afterward he regretted it and went. The man came to the second and said the same thing; and he answered, ‘I will, sir’; but he did not go. Which of the two did the will of his father? They said, 'The first.'” (Matthew 21:28-31 NASB)
"Now when they heard this, they were pierced to the heart, and said to Peter and the rest of the apostles, 'Brethren, what shall we do?' Peter said to them, 'Repent, and each of you be baptized in the name of Jesus Christ for the forgiveness of your sins; and you will receive the gift of the Holy Spirit. 'For the promise is for you and your children and for all who are far off, AS MANY AS THE LORD OUR GOD WILL CALL TO HIMSELF.' And with many other words he solemnly testified and kept on exhorting them, saying, 'Be saved from this perverse generation!' So then, those who had received his word were baptized; and that day there were added about three thousand souls. They were continually devoting themselves to the apostles’ teaching and to fellowship, to the breaking of bread and to prayer." (Acts 2:37-42 NASB)
Always remember, people who are genuinely called will respond, in faith, to the Lord's own draw on their lives. Such a response must be deliberate, carefully considered, genuine, and lasting - in order to be legitimate and result in salvation. The typical "altar-call" is charged more with emotional energy and appeal - or even a sense of pressure - to make a decision on the spot. Take note of the way, on the day of Pentecost, the message first had to go deep into the hearts of the hearers, causing them to beg to know the way to respond. Peter took the time to carefully continue with exhortations and instructions, before baptizing them. Then, notice the newly-born believers were sure to stay devoted to sound teaching, fellowship and prayer.
Perhaps, those who are genuine evangelists - or wise servants sharing Christ in any way - serve God better by simply preaching the (whole, honest) gospel, waiting to let people show they are ready for more help - which may or may not be from the same Christian(s). Also, for anyone who has heard the Father and comes to Jesus (again, I refer to the John 6 passage quoted above), the Holy Spirit will, at some point, be poured out, affirming the Lord is the One who is at work to bring people to repentance.
True repentance, to be sure, is a wonderful thing! However, let's not wonder the reason people don't just jump up and quickly repent, at the call of modern-day evangelistic methods and meetings. For that matter, let's not wonder or be impatient, about anyone's response under any circumstances, trusting the Father will draw and give the person clear opportunity to repent - on His terms and in His time!