I recall NorthShore placing instructions online for "preparing" their diapers, which basically involves folding the crotch down befor tapnig up, so the diaper gets a "V" profile in the crotch instead of a "W". W can be more comfortable but is muich higher risk for leaks.
For daytime wear, a W is preferred for me because my pant crotch is going to win eventually, and if my diaper is in a V, it's going to be to one side or the other, and that is much worse than a W.
Overnight however, I always make sure my crotch is in a V configuration so I don't leak. Sometimes that makes the rear cave in though. But that will fix itself once the material gets wet. It's best if the leak guards don't see any action at all, it's best to keep the wetness as close to the centerline of the diaper as possible. Actually the shape is generally a "V" but in reality is more of a "mushroom" shape, widening out a tad bit at the bottom. The material is going to swell when wet, so you don't want the channel closing up completely if you can prevent it. Done perfectly, when you wet, the first warmth you should feel is at your lower back. That means you're keeping liquids far away from the sides of the diaper, and filling in starting in the middle back of your diaper, where the best capacity and absorbency is at.
