So here are a couple of paragraphs that *I think* might do a better job of explaining things than I can (why not go to the source than have me put my own spin on it):

https://github.com/ReactiveCocoa/GHAPIDemo/blob/befc3f73b9c30fd8679230cdc02d1f5793b705e4/GHAPIDemo/GHDUserViewController.m#L138-L151

https://github.com/ReactiveCocoa/ReactiveCocoa/blob/fc32fc06d398a99cd7c4c28e102d1ffb4a2e3cf9/Documentation/DesignGuidelines.md#side-effects-occur-for-each-subscription

(Hopefully this also addresses your questions from [here](https://github.com/cdzombak/thingshub/pull/1#discussion_r8921419))