I keep a battery maintainer on just about everything that has a battery at my place, the exception being my Ram 3500 and my wife's Honda Ridgeline. They both get enough activity that the battery stays charged. Since I've gotten the Valk Trike I've ridden it a bunch and the two wheeler not nearly as much. Regardless they both have battery tenders on them.
I still start everything and let it warm up to operating temp about every other week. Both Valks, the zero turn mower, the Kubota tractor, everything gets run up to operating temp at least twice a month. Knowing I wanted to ride my two wheeler last week, I started it and did my normal thing.
But, I got distracted when I shut it down and used the run/off switch on the handle bars to kill it. That distraction (and my two working memory cells) allowed me to walk off and not turn the key switch off. The next morning, I barely got a grunt from the old girl. No start, no joy. Started looking for a battery, No at Walmart, no at O'Riley's, no at another couple of parts stores so, I ended up at Advance Auto and of course, they only had one and it was their most expensive battery.
$124 + tax. I was pissed, the Wally World version was about half that price with the same warranty.
But, it is, what it is. I knew that battery was "elderly". If I hadn't left that key on, it would have lasted quite a bit longer. I'd like to say Live and Learn but, that may not be accurate in my case.

Rams