What you were taught about asking God to forgive you at the end of each day is both commendable and wise (and it's a practice I've always tried to follow in my own life).
Why is this a good habit? One reason is because if we don't stop to think about our sins, we'll probably overlook them -- and if we do that, we'll keep on doing them. Just as our hands grow calloused and insensitive if we keep rubbing them against something hard, so our hearts can become calloused and hardened to our sins when we don't face them and seek God's forgiveness. And if we never ask for His forgiveness, we'll also never ask Him to help us overcome them.
But the main reason we need to deal with our sins as soon as possible is because sin cuts off fellowship with God. If we have given our lives to Jesus, we are still members of His family if we sin -- but our fellowship with Him is damaged, and we no longer are close to Him.
What are you overlooking? You're overlooking your own sins -- even if you aren't aware of them. The Bible says, "If we claim to be without sin, we deceive ourselves and the truth is not in us" (1 John 1:8). Remember: We sin not only by what we do, but also by what we fail to do -- including what goes on in our minds. Ask God to help you face your sins -- and then seek God's forgiveness.