There are many possibilities of checker patterns some of the limitless combinations are listed below:

So how are they done? Whenever I would see them on a model I would say its impossible and even make fun of the painter spending years to do them ( I was jealous! ).

Finally I found the courage to try them and here I give a little easy tutorial for all of those fellow painters who haven't given it a try!

Remarkably it isn't at all hard! And doesn't take a long time maybe like 5 minutes per each application of paint, so if the paint would dry instantly that would be like 20 minutes only per side of the horse!