I always prewash. It is a habit I have had for years. No surprises that way.

I found out the hard way that fabric does shrink when starching, so now I best press my fabric before I cut it, I don't prewash

Hi Tom, SORRY for your problems. Yes cotton does shrink, it can shrink from such a small amount that it doesn't matter or it can shrink inches. We've all had this happen at some point in time. I know that your heavier weight tighter weave cottons don't shrink as much as your lighter weight looser weave. Most of the time at the larger fabric (the big chains), and hobby stores have the biggest problems with shrinkage on the "big sale fabrics". I bought them because I liked the print or the color, but I know that I'm going to have to deal with shrinkage. So if I need to end up with X amount, then I know from past experience to purchase I make it double the amount I need just in case I have a lot of shrinkage. Any that is left over can be used in something else, as it has already shrunk. Good luck

I have had as much or more shrinkage from some lqs fabric as from some " other" fabric.

Note the word"some".

That shrinkage seems a bit extreme, however, this is one reason why I always wash and dry my cotton fabrics before using. I seldom iron clothes, however, I set up the ironing board, facing the TV, put on a favorite movie or program and iron away. Sometimes, I will take the fabric out of the dryer while still slightly damp, which works well for ironing.

I bought 118" wide backing , good stuff, not cheap, it shrunk to 108" so nothing surprises me anymore.

Interesting discussion on wash vs. no wash. I have prewashed my full cuts of fabric. But, I quilt with a lot of precuts. They specify not to prewash. Yes, I have heard of the swish and rinse method for the precuts. I admit to being lazy and just wanting to I throw everything in the washer.
Has anyone tried using lingere bags for precuts in the washer?

Always pre wash.

I generally don't prewash but I do starch and steam-iron. A block I made yesterday from yardage and pre-cuts was so off that I took it apart and re-measured my pieces. All of them had shrunk from the pressing the seams just enough to make the block wonky. So I put the yardage (Timeless Treasures) in hot water and hot dryer - it shrunk 3.25 inches! cross-wise. I put the pre-cuts (Moda) in the sink - no agitation, just to wet them, and they raveled so much as to be useless. So lesson learned, pre-wash yardage, do not soak pre-cuts.