I don't think this woman was a sewer. Hopefully, she'll find someone to help her add headers and hems and some extra inches.

I would have said be sure to remember to add the hem and rod casing amounts to your total needed and the tie backs if you are using them. If she gave me a huffy look I would have smiled and said I'm nosy.

Maybe she can come back for enough to add a ruffle or a add on header. I probably would have said something if it dawned on me at the time what was happening. Many times that kind of thing doesn't strike me as to what was said until too late.

Being afflicted with bossy teacher syndrome, just kidding, I'm not that bossy, I probably would have if I thought it would have been well received.

I would probably have said something if I noticed the problem, but I would more likely be focused on my purchase and trying to decide how much of each fabric to buy. Don't beat yourself up because you didn't speak up; she will just come in and buy some more to complete the project. Or maybe she was making cafe curtains and they would start half-way down the window, or perhaps she had another fabric that would be combined with what she bought. I no longer expect the person in JoAnn's or other chain stores doing the cutting to have any knowledge about sewing, although it's a pleasant surprise if she does. Sometimes I'm asked what I'm making and I say I'm just adding to my stash. Sometimes the look I get tells me I might as well be speaking Greek.

I think I would have said something

I would probably have said something as well.

I would have offered my opinion, worst that would happen is she wouldn't take your advice; but you could have left knowing your did your best to help.
It is terribly annoying that help is not properly trained nowadays in many stores; and is VERY annoying when they try to pretend they know what they are talking about even.

Me too.

I agree with your comment; in the first place the customer is always right and maybe the customer had other ideas with what she was purchasing.