cheers, reason i ask is because i just gave the 100 pushups a try and couldn't manage the 3rd week program even though i can max 19/20. Serie 4 and 5 i had to take a little longer rest, and only managed the 14 max on the last set rather than the suggested 15, plus my arms went floppy =/
You should aim for no more than 1 minute per set and on the final set I used to have 2 minutes before I maxed out. Now (4 months later) I strictly rest 30 seconds and when my watch bleeps at 30 seconds I start my next set.
I pretty much stick to around 30 seconds, maybe 60 if I need it and then do another set. I dont rest between exercises on a circuit other than the time it takes to move positions for the next exercise and then ill rest for 60 seconds between my circuits before starting another one.