Mine vary like many of you quilters, but I have a favorite.
Quilt in a day? You bet! I'm making bus quilts now for a boy's choir who travels some distances to jigs, and often has to be there early to practice (with an orchestra or other groups) and needs "down" time to rest up for the evening performance. I use the same system for "charity" quilts because they are so quick (not counting piecing to get the right size across-pieces, if necessary).
#1 - have double-sided sticky batting on hand aprox 42-44" wide and cut it to be 55-60" long;
#2 - dry-iron and attach fabric, pieced or whole (according to what you have on hand)-- this will be the backing;
#3 cut fabric 6 to 12" wide across a piece of fabric, selvage to selvage (you end up with the same size as the width of the batting);
#3 - sew the first piece at the top edge, dry-iron it down;
#4 - put the next piece on top of the first, right sides together and sew the second piece to the first, and dry-iron it down;
#5 - continue step #4 until you reach the bottom of the batting;
#6 - If the width of the piece is more than 4" (6" for sure) then you will want to do a few quilting stitches from top to bottom;
#7 - put a narrow boarder on, machine sewing with a semi-wide design stitch so it catches all edges in without stressing out;
# HINTS - You may be happier if you at least estimate how wide you want each piece to be so the last piece is about the same as the others;
But realize that different width of cross-wise pieces will also add interest (and use up some pieces you may have in your stash at the same time).
Now I am going to go on to the picture place and see if I can send a picture of one of my quilts so you can get an image idea of what on earth I'm talking about (for those of you who are "challenged" like me).