If you read “The Sermon on the Mount” Mat:7:/Luke:11:9, you will see that it starts with
M't:5:1: And seeing the multitudes, he went up into a mountain: and when he was set, his disciples came unto him:
M't:5:2: And he opened his mouth, and taught them, saying,…
Christ them makes a number of statements and, as He is incapable of lies, we must believe Him.
M't:5:12: Rejoice, and be exceeding glad: for great is your reward in heaven: for so persecuted they the prophets which were before you.
M't:5:13: Ye are the salt of the earth: […]
M't:5:14: Ye are the light of the world. […]
M't:5:16: Let your light so shine before men, that they may see your good works, and glorify your Father which is in heaven.
Jesus, whose Word is Law, makes no mention of the level of faith required. The people who came to The Mount, came to hear Him. We can imagine that some came out of curiosity and others because they were already “of the faith”. And yet He promises the same thing to them all.
In Luke, the words are place in a difference scene but nevertheless, we see
Lu:11:10: For every one that asketh receiveth; and he that seeketh findeth; and to him that knocketh it shall be opened.
Lu:11:11: If a son shall ask bread of any of you that is a father, will he give him a stone? or if he ask a fish, will he for a fish give him a serpent?
The idea of “If a son shall ask” also recalls the parable of the Prodigal Son and in neither case is the level of faith described – only, we assume, “some” faith. This is because we will all have different levels of faith, yet Jesus’s words cover us all.
Now, as human experience has been that, as you say, some prayers are answered, some are not and for some, the answer is “wait”. If you pray to the milk-jug, the answers are the same. It then becomes impossible to say whether this is just ordinary chance or the actions of a deity.
But what we can say is that it really does not matter what you pray to, the chance of you getting the answers “Yes”, “No” and “Wait” remain the same.
This is the same as:
A: “What are you doing?”
B: “I am setting up my machine to scare away elephants.”
A: “There are no elephants around here.”
B: “Yes, it is very effective isn’t it?”