(IAAC) Supernova

I've recently become interested in observing supernova. I've only had a
chance to see one. I'm going to try for another as soon as I the skies
clear in this area. I have a question. The recently discovered supernova
I've been reading about all seem to have similar brightening and dimming
patterns. Is there actually a pattern or is it just coincidence? It
seems to me the recent supernova brighten and dim over a period of maybe
a month. 
Harold Williams 
Head Astronomer & Janitor
Northeast Philadelphia Deep Sky Observatory