It's two handed swings. If you change it, fine, but then its not the program. At my blog, danjohn.net, you can see how we added a lot more to this, refined the lifts in-between and play around with a lot of different things. Yesterday, for example, I did 250 swings and Group A and Group B on the 15/35 workout. So, the swings were solid throughout, but I also got in my work on the ground, fundamental lifts and some stretches.
I am not a fan of one handed swings for me and most the people I work with in my gym. We have asymmetry issues and, well, that's it. I far prefer doing 500 swings five days a week, or 250 forever, and using the swing as a once stop GPP.
Again, I know that everyone wants to change programs. We did this one, nailed the 10,000 reps reasonably, got the results, improved our other lifts with the WTH effect and now we are looking at ways to improve it. But, we did the program first.
I walked into the Sistine Chapel and saw Michelangelo on the scaffolds. I yelled up: "More blue."
That's how I feel when I see people look at a program and immediately "make it better." My best success in my career has been following a program exactly (ROP, Soviet Squat, PBBC and OLAD all come to mind) then tweak and discuss at the end.
So, as you can see with FlyingPig's insights, you did 25/25...which is fine, but mind boggling boring and hard to remember over a few weeks. With our system, we just throw something (lately mini-bands or lawn golf balls) into the middle. Once you see four balls in the middle, you finish that set and go home.
The mind and free will are at task here. 500 Swings a day is a lot and, frankly, it is nice to just follow the path and just count 100s.