nearly 18 months ago I got a notion to make some fancy stakes for securing concrete forms based on a vid I'd seen on youtube. last week I was making some steps outside the back door at home, a job that required a reasonable degree of accuracy in the formwork so I got to try out the pegs.
I thought they were the absoulte business. I was going into some very hard ground so much more easily driven than a 2x2, the way you could really screw them tight to the form, the solidity of the whole formwork when done, the ease of adjustment and tweaking when setting up by myself, everything was just easier with them. I have 16 from 2 sticks of steel and think they were a very worthwhile investment.
Although in the interests of full disclosure I would also point out it's not that hard to drive a pointy piece of 20mm steel through a soil pipe