Same experience here with the short lived Walmart batteries.
I'm not sure if it'll help extend battery life or not, but 3 years ago I got an Optimate 6 battery charger /maintainer.
I had a one ear old Walmart lawn tractor battery when I got the Optimate 6.
During winter storage of the battery inside a 65* area, 2-3 times during the winter months I'd hooked the Optimate up to the battery and let it do it's charging/maintaining. This past fall I sold the garden tractor with it's battery, and the battery was still going strong. So that Walmart battery lasted 3-4 years. Did the Optimate 6 help extend the life ? Who knows. Longer test will be needed.
I now have 3 batteries in storage through out the winter, and 2-3 times will hook up the Optimate to each of them, hopefully I won't need to buy batteries for awhile.
A buddy of mine turn me on to the Optimate, he had an earlier version, and he swears by them actually bring batteries back to life.
There is stuff on youtube about The Optimate 6 also.
I got mine for a little less than $100.