It's different for home processed chickens, is my understanding. When you process yourself, you control the cleanliness of your setup, the processing area, how cleanly you gut, how many rinses you give the carcass during processing and afterwards, how quickly you chill after finished processing, etc. I checked him each day, and he smelled perfectly fine. I wouldn't push it past 7 days just because I don't think it's a good idea, but I know 5 days is common from what I've read on this forum. Took that chicken a while to not have rigor going on, and I had to find a minute to cook it, which is not easy around my house. Meant to cook it at 5 days, but 7 days is when I had a minute. Tasted fine, and we're all well. Smelled great in the bag prior to cooking.
Grocery store meat, yeah, use or freeze in 3 days tops - I've had too much chicken go bad on me. It always seems somewhat slimy when I open the package - I'm much happier with chickens processed myself, for all that it's a boatload of work.