@Bumblebuncher I don't know how much fabric I had in this particular length, maybe 6 or 7 metres.
I'm going to pop this discussion out into a new topic as the answer has turned out to be quite lengthy and might be interesting to others who might give you different answers!
I think it goes back to something I read in a book - Sewing A Travel Wardrobe by Kate Matthews from 1999.
The Six- Yard Wardrobe
Designer Joyce Cusick has a busy life that includes lots of travel both for pleasure and business. She also loves to keep an eye out for special fabrics wherever she goes. She developed a 'six-yard wardrobe' approach to travel sewing after several trips to the local fabric store for more of the same material. She started with enough of the royal blue linen blend shown on these pages to make the skirt and slacks. She liked working with the fabric so much that she went back twice for more, to make the jacket and then the dress. The garments have become a well-travelled all-weather wardrobe and she reports she's worn them in various combinations at least three hundred times.
Joyce realised that if she consistently bought 6 yards of solid colour fabric, she would always have enough to sew a complete basic wardrobe that includes jacket, slacks, skirt, top and sometimes a dress.
Knowing this ahead of time makes it easy and fun to shop for fabric. She doesn't have to know precisely how much to buy of a good find at the fabric store or street market, but she's always sure that there will be enough to make up a well-coordinated grouping of versatile garments.
Today, all of her travel clothes are created from six-yard wardrobes, plus a few print accent garments and an assortment of accessories.
Joyce must be a smallish size, and likes sleeveless knee length dresses as there's no way I could get all of those garments out of 5.5 metres in my size and style preferences. I think I must've worked this out after buying a few 6m lengths, but then thought that was still useful for capsule wardrobes, and particularly for the ideas I had at the time for sewing interesting trouser suits for work.