Fresh Maxima breaks about 10% above its rated strength. Then after 1 year (stored in the dark), it will regress to the label. Fresh 12lb UG will break at 13.5lbs or and then fall back to 12lbs. If it breaks at under 12lbs, retire the spool.
When I used mono mainline and I was on a destination week-long trip, I'd have 2500 yard/meter utility spools and change the entire line every-other-day if hooking bigger critters or the water was snaggy.
* * * * *
The separate topic of "Do I set the hook again if I don't like the first hookset?" is a different one, unless you are thumb locking the spool so there's zero give. (Even then, if it's a 100% mono setup you shouldn't ever break fresh <10lb line on the hookset: too much line stretch.) My advice on the 2nd hookset is to do it, but wait until you're at a 90-degree angle to the fish and then sweep the rod parallel to the surface. The shorter the line, the better. I don't break these fish off, but 20%-25% of the time the hook pulls out. I figure that the fish was a goner anyway so I saved us both some time. The other 75%-80%, I either land or lose to a different act of incompetence.