Hmm, i think they are equally likely
My line of thought is :
a) Each number from 160 - 199 has a probability of 1/40 of hitting exactly 200 on the next polling test. At this point i thought, hey this (1/40) is more likely than 1/200 but nooo...
b) We are in this range, i.e.160-199 only 40/200 of the time so, 1/40 * 40/200 = 1/200, which is exactly same as the case of incrementing by 1.
So no matter the increment, both codes execute polling once every 200 nodes.
However, there is a problem though with the later because you are not guaranteed to do polling every 200 nodes. Infact, my engine was failing on time multiple times using the second approach which led me to this question.
The second approach has a large gap between hits on average. A maximum of 200x larger gap between hits could occur for the second approach, which is probably why it was failing on time.
Daniel