The challenge of folding flagstone is quite appealing. it requires a lot of patience and persistence. Even after you fold the standard grid there are still many more folds to add. It's a whole lot of prep work before you ever begin the actual creation.
That's probably true of most origami tessellations. All the work is in the prep. Then you allow that work to pay off in your resulting collapses.
With flagstones you also have to work both sides of the paper. The design will have triangles on the back that need collapsing in order for the front structure to work together.
I am always grateful when origami artists publish their crease patterns. And Peter has many published on his flickr account.
The one for this design can be found at: https://www.flickr.com/photos/syngola/4968245966/in/album-72157624777290209/
To me it's small pointy stars which are surrounded by much larger flower like petals. I mostly work on a 32 iteration grid. This design fits comfortably, but a larger grid would really showcase the repetition more beautifully. This is evident in Peter's crease pattern diagram.
He has imagined some wonderful designs and patterns that he's shared with the community. It's much appreciated.
Although there is a lot of fun to be had trying to figure out others' designs without a blueprint.