I ordered this bra in the 42 C size after buying two bali bras in 38c.  I had worn 38 C since I was in my 20's...about 40 years ago.  Anyway, when the balis arrived, they were tight...but still usable simply by adding an extension which I make myself.  So, using the measuring guide that Amazon thoughtfully supplies, I discovered that I actually am a 42 C now...sigh....hate to admit I'm a bit larger than I was in my 20's, lol.
Anyway, I used to always use the "twist" method.  But because I now had the proper band width, I did not have to do that anymore.  But, because of severe back problems, I cannot reach my arms backwards to fasten it so I came up with a great solution.  I fastened the bra first....then stepped into it like a pair of pants, and just pulled it straight up to slip my arms through the straps.  This solves two problems for me....first of all, getting it on without twisting it, and secondly, this also "hoists" the girls up naturally.  As you pull the bra up, the girls get hoisted up along with the bra.
Now.  I ordered the bra in "Sailor Blue".  I've never seen one in navy before....and loved the color.  When it arrived, and I loved it, I ordered another in the darker pink color.  Then, I ordered another one in the same Sailor Blue.  There was a very good reason for this.  My first Sailor Blue was no longer wearable.  But I could not return it...because it would not have been eligible for a refund.  The reason for returning it was because my sweet, adorable, loving 10 month old Brittany Spaniel had gotten a hold of it...and very neatly chomped through the left strap just above the band in the back!  Sewing it would be an answer, but then the cups would be "lopsided" and because of the extremely reasonable pricing, I simply ordered another in the same color.  "Isabelle" is still in her chewing stage...of which I discovered some dogs can stay in for up to two years!  The way she had gotten hold of it in the first place was because it was still on my dining room table inside it's plastic bag.  She is a very "lanky legged" dog and was able to reach it....and first chewed off the bag, then chewed through the strap.  If I listed everything that dog has destroyed with her teeth, it would take volumes, lol.
Now.  As to the 18 hour claim?  YES YES AND YES!  You CAN wear it for that length of time and even longer.  Before my canine "Jaws" had gotten hold of it, I had the chance to wear it ONCE.  I had it on from 6am till around 3am...and found it to be as comfortable as it was when I first put it on.  The straps, I was at first wary about...the padded part...but they proved to be super comfortable.  No digging in, no slipping off the shoulders, nothing.  They stayed in place perfectly, AND...as I have had to do in the past with other bras....there was NO CONSTANT ADJUSTING it!  With my other bras, I have always had to reach up and under to pull it down and readjust it.
On many of the negative reviews:  I do not understand what the reviewers mean by "madonna pointy look"...This bra is NOT POINTY at all...at least it was not on me.  I don't see HOW it can be pointy.  In order for it to be "cone shaped" or "pointy"....you would have to have FOUR seams all meeting at the tip of the cup...this bra has a seam going across horizontally...and that's all the seam there is on the cups.  This does NOT create a "pointy or cone" look...I don't understand what the negative reviews mean by cone or pointy then.  Perhaps someone could explain it to me.
Anyway, when my new "Sailor Blue" bra arrives, that along with my pink one, I guess I will have to put it away immediately, lol...in a tightly closed drawer where all my other underthings are.  I have not even tried on the pink one yet but because the Sailor Blue one was so comfortable, I know the pink one will be as well.
Don't be afraid to try this bra...you will LOVE it...just keep it away from any puppies you may have around....