As with many fishing illustrations, there's a good spiritual lesson in that. Making a God-honoring decision is not only about doing the right thing, it's also about doing it at the right time. Better to wait patiently with a precision cast into God's perfect will, than to get impatient and cast here, there and everywhere, perhaps missing God's best in the process.
And, yes, God is sovereign - even over the unwise decisions we make. But often times we can save ourselves a lot of pain and heartache if we will just wait for His best.
"Wait on the Lord. Be of good courage and He will strengthen your heart. Wait, I say, on the Lord!" Psalm 27:14