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There is no story in the scriptures of anyone laying out a fleece in prayer. Gideon laid out a fleece for God to show him YET ANOTHER SIGN when he was commissioned by God to defeat the Midianites on behalf of the nation of Israel.
When the angel of the LORD first appeared to him at an earlier date, he asked for a sign. It was his idea to cook a young goat and bake some bread for the angel to consume. He did; the angel touched the tip of the staff he was holding to the meat and the offering was totally consumed. Then the angel disappeared. Gideon marveled at this sign and thought he was doomed because, "I have seen the angel of the LORD face to face!"
He wasn't confused about any of this. He wasn't unsure of whether he had been spoken to by the Lord. He knew he'd been commissioned to lead the people against the Midianites.
That night he and ten of his servants tore down the altar the people had built to Baal, and built a new altar to Jehovah. The next morning the people wanted to kill him for doing it. His father Joash spoke up for him and quieted the people.
"Soon afterward" the Midianites and others rose up against Israel and Gideon asked for another sign, the fleece ordeal. God obliged; twice...
Apparently, this test was a confidence builder for Gideon. He no longer seems afraid. When his army was pared down from 32,000 to 300 by God, he didn't complain at all.
I believe it's easier to trust God when it's clear it's him or nothing; when there's no safety net.