There clearly are sins that hinder prayer.
1 Peter 3:7 Likewise, ye husbands, dwell with them according to knowledge, giving honour unto the wife, as unto the weaker vessel, and as being heirs together of the grace of life; that your prayers be not hindered.
12 For the eyes of the Lord are over the righteous, and his ears are open unto their prayers: but the face of the Lord is against them that do evil.
Psalms 66:18 If I regard iniquity in my heart, the Lord will not hear me:
The normal Christian life is one of daily answered prayer. The Lord taught us in His Prayer Primer (Matthew 6), to pray daily for bread, for forgiveness, for deliverance from evil, and also expect to get the answers daily.
This is how Jesus lived, in daily unhindered communion with His Father. He said to His Father,
John 11:42 And I knew that thou hearest me always: …
Jesus taught that we should be in a daily relationship with God in which we ask and receive, seek and find, knock and the Father opens the door.
John 16:24 Hitherto have ye asked nothing in my name: ask, and ye shall receive, that your joy may be full.
The Christian living in the wil of God can live day by day in the fullness joy of having his prayers answered.