I run 30lb Maxima on the two reels I match with my "5" power mooching rods that I use for fishing deep, like in the mud out on the banks, and if we're into larger sized springs. I run 25lb Maxima on another two reels I match with "3" power mooching rods for fishing shallower than 100ft and/or for coho and small springs.
I check the last 10-20 ft frequently, after every fish, every few times up and down on the rigger, etc, and even if no nicks or kinks cut it off and re-tie every couple of days at minimum. Inevitably if you fish enough your gear will get fouled which usually means serious twists - I cut it all off as I don't want to hook the fish of a lifetime and lose it because I was too cheap or lazy to sacrifice some line. Start of the season I strip off 50ft and cut it off. Once I'm down about 1/5th of my spool it is time to strip off the remainder and put on new, about every 2-3 yrs for the amount I get to the coast and fish.
A tip I was taught to save on the amount and cost of re-spooling mono is to use a good backing to fill your spools so that it only takes 200-220 yards of mono to fill your reel (don't over fill right to edge of spool, asking for all kinds of trouble!). Thus, when replacing, you just have to buy the Maxima "One Shot" spool, which is 220 yards in the 25 and 30lb size. That's 660 feet of line, more than enough for downrigger fishing and hacking off the worn bits liberally for a couple of years.
Cheers!
Ukee