I know Pavel loves these ( actually one arm one leg ), and I will admit they are fun but I honestly don't train for them, if ever. I did read a boast on a thread where somebody said they could do 70+ but no idea on form and saw a lot of ppl over a dozen. I can't remember how many I used to do. I'll say I'm under 10 on each just to guess.
However, I was playing with them at the request of someone I was chatting with. I never really followed a program to get them since I got them when I was a teenager. I think we just did them and that was that. We did at least a dozen if not 2 or 3 of different kinds of pushups probably.
Anyways, I notice hand directly under the breastbone/solarplexus is more difficult than when the hand is off center or under the shoulder.
If any of the other mods can think of a better place for this, let's move it there. I thought about basic strength and community as well and just gave up.