See alltheplaces.xyz for continuously updated straight-from-the-primary-source opening hours of chains of shops and restaurants, public facilities such as libraries, etc. This is probably as accurate as it gets AND you have the confidence of knowing exactly where the data came from (down to the URL) and when it was last checked.

Some OSM contributors go brand-by-brand/operator-by-operator in making sure OSM features have the most up-to-date opening hours added to them from matched ATP features. As such, OSM may be fairly accurate for chains too.

For a standalone shop or restaurant the opening hours situation is usually still better with Google Maps rather than OSM. There aren't enough OSM contributors who care enough to check and maintain opening hours for every shop, restaurant, fuel station, etc.