One thing you seem to overlook is the fact that Jesus said I am the way the truth and the life and no man comes to the father but through me... Prayers to Mary for intercession are a waste. And in answer to your question, asking a person to pray for you isn't the same as praying to Mary to get her to get your prayers answered. Mary has no way to get to God on your behalf. Not to mention the fact that Mary has no ability to hear anyone's prayers anyway.