How long to run…

Exactly. I don't care that it's 10+ because it's safe up to 28 FC for my 70 CYA. An 11 or 12 isn't even close. The added bonus is I have a 2 or 3 day reserve at all times, allowing me a bigger window to catch a cell issue.

A monster storm could come knock out power for 2 days and I'm already good.

Anything else like 1 high UV loss day or a baby storm is a joke.

Also realize that the daily loss starts low, peaks mid season, then drops slowly back to low. In the spring and fall, 8 FC may be a 3 day supply the same way 12 is in July. It's a moving target but the key is to have plenty to spare for that point in the season.
 
Do you use a meter?
I don't but that's a viable option.

The pool still swings and if you test at the low point of the daily cycle after a particularly sunny day, FC will probably be a hair under 10.

Or for the weekly PH test once you know how your pool behaves, lower the SWG the day before and it will be ok to test PH the next day.