I get 5-10 per weekly update, but sometimes at the end of the week I end up with slightly less than at the beginning (-11 -12)
Also fun fact I've been on the staff picks a few times and every time it has been vastly different, I don't remember the exact numbers but the first time I went from 100subs to 600, second and third time I gained 50 each, I pretty much didn't even noticed, fourth it was about 300subs, soo I guess it's just luck and whatever mood people are feeling at the moment
And another thing, the only way to keep my numbers from decreasing along the week seems to be bringing traffic from outside which is an entirely different beast