I don't think the volts going in matter as much as the amperage, when you are idling at low rpm'* the alternator is not doing much to charge the battery back.
I think it is good to manually top it off once and a while, but the load testing is probably overkill.
I keep a battery maintainer on my battery 24/7, but I do not drive daily, and I have a bit of a parasitic draw that I need to track down, I have put it off for a while, but eventually I'll work on tracking it down, either way I like to keep the charger on there, my current battery is like 2 years old, and it starts just as well as it did when it was new.
My advice, manually top it up from time to time, and not worry about load testing it, when it gets a totally dead cell, and won't hold a charge anymore just replace it.
You have an Optima Yellow Top right?
If so it should last twice as long as traditional batteries.
Here is a good read on those batteries.
How long will my car battery last? | OPTIMABATTERIES
""The key to long battery life, regardless of brand, manufacturer or type, is proper voltage maintenance. Fully-charged, our REDTOP® batteries will measure about 12.6-12.8 volts and our YELLOWTOP batteries will measure about 13.0-13.2 volts. Keep your batteries fully-charged whenever possible and you'll help maximize both their performance and lifespan, however long that might be. - See more at: http://www.optimabatteries.com/en-us/experience/power-source/how-long-will-my-car-battery-last/#sthash.ZlzN4WGM.dpuf""