The big processors are always held to a more punitive time frame than everyone else, so grocery store timelines are probably the safest as long as processing is done correctly and in a mostly sterile/sanitized environment.
However, there are a few factors that are in play for the average person:
After processing, loose packaging will give you the least possible timeline. Vacuum sealing will give several years, chamber sealing will give you about double that.
Freezer temp should be zero F or less for the longest storage, "just frozen" will be considerably less. Most fridge freezers won't do well for long term storage. Chest freezers suck for organizing, but will be the most efficient at lower temps and the cheapest square footage.
We have pork/beef/fish/poultry that taste just fine after 3 years, that are vacuum sealed and kept cold at zero F. The chamber sealed meat doesn't even lose its color after a few years.
BUT, don't take chances! Do what's comfortable for you and cook everything to appropriate temps before eating.