No, the pinwheel blanket actually increase at 10st intervals. Similar principle though. The pinwheel uses YOs to increase, I used Kfb to increase.
Any form of increase is acceptable. It can be done with any count for increases as long as your markers are placed evenly throughout. The increases must be balanced with knit rounds. On 6 sts. it's every 3rd round. On 8 sts, it's every 4th round. Not sure on the 10 st, you'd need to check the pattern.
If you'll notice, this one is hexagonal. The higher the st inc count, the rounder it will be when completed.
I'm working on a rug that will be felted, that is oval.