Ptolemy's model is less accurate than Copernicus', but it is said to have been in use for a long time.
What was the Ptolemaic model be used for?
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One specific application was the eclipse prediction. For example, Columbus used a predicted Lunar eclipse at least once, trying to determine his longitude. He was not very successful.
Ref. S. E. Morison, Admiral of the ocean sea: a life of Christopher Columbus.
One of the main applications in the Middle age was computus, computation of the date of Easter, which is changing every year. Ptolemy's theory of Sun and the Moon was used.
Remark. Applications to astrology were very limited. Astrologers used (and still use) a more ancient system, of Babylonian origin. Astrologers were not very interested in advancement of science, even at the time of Ptolemy. Of course, there were exceptions.