Ross Mac writes:

Can I get away with 3 hours or so??

Quite possible, especially in the winter.

Don't believe those rules of thumb. You can get away with what you can get
away with. That is, give it a try for a few weeks, and see how it works.

In the winter in SE Florida I turn the pump and chlorine off altogether,
and it takes some days or a week before I have to clean it up, IF you keep
the pH on the low end. The low pH is critical. Stuff doesn't like to grow
if you keep the pH on the low end of comfort and Langelier balance. High
pH will get you algae and cloudiness in no time.