even at the 20 hour rate though, how does that compare to a better quality battery that costs 3x as much or more?
I just checked, and the Optima Yellowtop battery in the same size has a 20 hour capacity of 66Ah, and costs $264.99. For a long term solution that needs to be uber reliable, I would definitely go with that. But as long as the walmart battery lasts the length of its warranty, 1 year, it looks like a solid value.
Hard to say about longevity. Many people think higher cost, well marketed batteries will automatically last longer, but the fact is any battery is damaged by abuse, and the easiest way to abuse a battery is to over discharge it and undercharge it, over and over.
In an application where highest capacity is desirable, Optimas would be the last battery I would choose. The same group size odyssey or Lifeline will have 33% more capacity and cost about the same. A Hundred amp hour Odyssey group 31, when bought as a Sears Die hard Platinum, costs $284 when not on sale.
Beware of clever marketing. It plays on ignorance.
There is no point in talking longevity of any brand battery vs another, if it is not going to be recharged promptly, fully and properly. The alternator is not going to do this on a deeply cycled battery, no matter how shiny it is. Additional charging sources will be required to reach true 100% state of charge.
I did not have good experiences with Wally World batteries in deep cycle applications. Failures happened when most inconvenient just out of warranty,and I was so angry I would not have taken a free replacement at the time, if offered.