I am of the opinion that it depends on what kind of adhesive you're using.  If you're using something like methylcellulose (MC) wallpaper paste or cooked flour/water, lay down as many layers as you want, then let it dry.  You can speed the drying by aiming a small fan at your project.  DON'T use heat, or you'll cook the outer layers into an impervious skin, and the inside won't dry.

If you're using PVA (white plastic) glue, you would probably be better off letting a  few layers dry before adding more.  Because it's plastic, if you put a lot on wet paper, the outer layer will dry and form a plastic coating that tends to prevent the inside from drying.

The only reason I know where you should let the initial few layers dry before continuing (when using MC or flour/water) is when you are using balloons or other inflatables.  With those, you may need to get some rigidity with your first layers because the inflatable may start deflating.  If it starts deflating while your project is still wet, the whole thing may collapse.

Sue

Hi
Fairly new to this myself ive found getting at least 2-3 layers on first gives the peice a little rigidity when using balloons, and then only 1 max 2 layers after that because the more you mess with it the more likely it will distort. Allow to dry before next layer .If using some form of mould don't be to eager to take the bowl off the mould. i have at least 12-14 layers on and i never quite allow it to dry right out because it shrinks. I use pva /water mix .

Sue.