Why were miracles and clear signs not used in all instances to support the Prophet's call, peace and blessings be upon him, even though they were used in many cases?

Allah, through His Prophet Muhammad, peace and blessings be upon him, performed many sensory and intellectual miracles that prove the truth of his prophethood and the comprehensiveness of his message. Among the sensory miracles are those witnessed by his contemporaries from his birth until his death. Among the intellectual and rational miracles is what the Holy Quran contains of various sciences. Allah challenged both humans and jinn to produce anything like it, saying: "Say, 'If mankind and jinn were to gather in order to produce the like of this Quran, they could not produce the like of it, even if they were to aid one another.'"