When working with scrapbooks, one important thing you have to take note of is the proper use of adhesive. Putting adhesive the wrong way may destroy your scrapbook and all your hard work. Like with paint, an even distribution pattern of adhesive is important, especially with lightweight surfaces. You won't want one corner of your surface to be coming off when another side is firmly sticking. That would, most probably, end with the medium being torn if it is paper.
You won't want to have so much adhesive on the back of your surface, either. Imagine if it is liquid adhesive and you put so much of it at the back of your surface. I can see three bad things will happen when you do this. First, when it dries, expect the surface (if it is paper or anything like it) to be stiff. The flexibility of the light surface is gone. It would be like you're working with cardboard.
Or it may be that the glue marks are seen from the front. What a nightmare. The surface (again, if it's anything light and delicate) will have wrinkles on it where you have put so much glue.
Or it may be that the excess liquid adhesive will make its way to the edges and leak. That is not a good sight. When it dries, you'll see all the glue markings scattered all over your surface.
Krylon Spray Adhesive tries to solve those problems. After all, like with paint, having adhesive sprayed is better than brushing it on the surface. Using a spray, the distribution of the adhesive will be more evenly distributed and you will immediately see when you put enough adhesive, thus preventing leaks and wrinkles.
When you can help it, spray it.