Meaning and purposeful placement (Psalm 145)

Excerpt from The Psalms of the Return by Michael D. Goulder (Sheffield Academic Press, 1998):
"With Psalm 145 the last part of Book V of the Psalter takes a dramatic turn.  In Psalms 139 - 143 the psalmist was beset by enemies who attacked him verbally and physically, who imprisoned him, killed his friends, and threatened his life.  In Psalm 144 the same psalmist prays for divine deliverance as the hour of crisis is at hand.  With Psalm 145 goes up a great paean of praise at God's faithfulness in answering the speaker's prayer, a paean that will continue through the concluding Psalms 146 - 150. . . Psalm 145, like 138 - 144, is headed "FOR DAVID," the last of the David series; whoever set the psalm here saw it as the culmination of the sequence, the response of the same psalmist who has been speaking all along, and who now sees his trials at an end.  To celebrate the wonder of his victory he has adopted the alphabetic format . . .Its feeling of triumphant praise has made it one of the most widely used of all psalms, and its joyful spontaneity suggests that it was composed impromptu (with a slip at the "nun-verse").  There is an obvious similarity of the third section of Book V, Psalms 135 - 150 to Psalms 105 - 118 first two historical psalms (105-6 / 135-6); then a celebration of the return from Exile (107 / 137); then a sequence of psalms "FOR DAVID" (older laments 108-110 / 138 - 144); next a turn to praise in acrostic form (111-2 / 145); and finally a series of praises marked out with Hallelujahs at beginning or ending."