I took a spreedsheet... I thought about it... and it will be in the next release...
Thanks for the good idea.
In the next release waiting times will be doubled after each failed connection. The candidate will be dropped once the number of failed connections in a row reach a configurable threshold.
There are still other cases where candidates get dropped though.
If you like to take a more detailed look on the old and new download activity diagramm check out these very technical images:
Swarming 0.7 Swarming 0.7.2
Gregor