The Lord may be slow to answer our prayers for many reasons. We may be praying for that which we ought not (DC 8:10). We may be praying without faith. We may be in a period of trial for ye receive no witness until after the trial of your faith (Ether 12:6). Even the Prophet Joseph wondered while praying, O God, where art thou? And where is the pavilion that covereth thy hiding place? How long shall thy hand be stayed? (DC 121:1-2) For these and other reasons, the righteous often don't receive immediate answers to their prayers. For this group of Nephites, the reason is because they were slow to repent. The Lord is not very sympathetic with people who only pray for help when things get bad, In the day of their peace they esteemed lightly my counsel; but, in the day of their trouble, of necessity they feel after me (DC 101:8).