Here is my 2 cents:
If your lacey project is a scarf, shawl, or similar shape...exact "gauge" won't be as critical as, for example, a pullover or cardigan where [COLOR=Red]exact gauge is critical[/COLOR] to the garment's correct size.
However, if your gauge is waaaaay off for a scarf or shawl...you may run out of yarn if you are knitting looser than the designer intended.
My recommendation: bite the bullet, grit your teeth, dig in and knit a gauge swatch "in pattern" (if she said so) or in St St (if she said so)...and measure the results.
It is never a waste of time to do proper gauge swatches. It also allows you to practice your lace pattern for a while!
My first NIGHTMARE caused by incorrect gauge was this (you'll laugh!): many moons ago, I knit my first aran (yeah, calbes, bobbles and all) pullover sweater...I was very ambitious! I knew nothing about gauge...so I just grabbed the needle suggested in the book...and knit away! When I was all done...knitting, seaming, the works!....my sweater was about a size 24! (I was a size 4!) It was supposed to be mid-hip length...it was knee length on me.
Gauge is so important.