I am a web designer, using grids in web design is pretty easy. I would really like to try and design 2d illustrations, though I am not good at drawing. Recently I keep coming across drawings (like the one bellow) what show the use of a grid.
These kind of grids seem to be "made up". For example, with the grid bellow, you can only create that buddha, were as if you wanted a grid for the apple (mac) logo, you need another grid! I am wondering
A) do designer always use such grids (or is the use of such grids recommended) and
B) can you direct me to some source where I can learn about these grids (I been searching in google and can't find any useful tutorials apart from images)