How long does the bleach stay potent if bottle unopened? I have never got a clear answer to that. Only a few months if opened.
https://www.scripps.edu/newsandviews/e_20060213/bleach.html
“Bleach can expire. After a shelf life of six months, bleach starts to degrade. Even in its original bottle, bleach becomes 20 percent less effective as each year goes by.”
As long as there is a drop in the jug, I’m using it. Better than nothing.
Dr. Laundry says:
The rate of breakdown increases rapidly when bleach is stored in extreme hot or freezing temperatures, or when a bottle is more than one year old. Generally, bleach stored at room temperature (~70°F) has a shelf life of one year, but after that point it should be replaced.
https://www.clorox.com/how-to/laundry-basics/product-usage-guides/shelf-life/
you could make a smaller amount (2 tablespoons diluted in 4 cups water) that you use up over several days for general countertop cleaning. However, when you are cleaning up after things that are highly likely to spread bacteria (like raw meat), you would want to use a freshly mixed solution.
ibid