(Pre-)shrinking linen

Some fabric dealers say their linen will shrink up to 10-15 % over the first few washes. Now, most extant linen garments have probably been washed several times, so if we use their precise measurements to sew an exact copy from unwashed linen, we'll end up with an item that will be smaller than the original once it's been washed—and probably disproportionate too, as fabrics shrink mostly in the warp direction. Did linen always shrink this much?
 

Measuring linen

In the Western world today, we think in centimeters or inches. For sewing projects that don't involve fitting, it's easy to think in round numbers; perhaps different ones depending on if we prefer metrics or Imperial units. But European women in the 18th century and earlier probably picked other 'round numbers' than we do now.