Every time I've ever heard somebody say, "I studied the Bible for years, and I studied it in depth," my first reaction was, "Bullshit!"
99% of the time, when you actually talk to these people, it turns out they got all their biblical knowledge from Sunday school lessons and Protestant sermons. In other words, when it comes down to doing any actual work, that is, Bible study in their spare time, they never did it. They thought about it; they talked about it, but when it came time to do it, there was always something else going on that was more important - the football game on TV, housework, yardwork. You could say that for the last 28 years, everything that happened in their lives took precedence over Bible study.
Think about it: they claim to believe in an all-powerful almighty God who loves them and adopted them as his children (John 1:12) ... and he wrote exactly one book for them to read ... but they can't spare 10 minutes a week for personal Bible study.
I was different. I expended great amounts of time and energy in personal Bible study, and I can prove it. Over the years, when I studied the Bible, I made extensive notes.