Well Karma must be dictating all the bad luck you haven't had with your batteries has been transferred to me!
I rode for over 20 years without a single battery failure. Like you, I used some of my bikes daily, abused others at weekends and let yet others stand around idle for months, or in bits. If one was dead, I'd just hook her up and 12 hours later we'd be off.
Over the last few years pretty much every one of my bikes has had battery issues.... Bikes used every day, bike sat still for a few weeks. Every one!
Over the last year I've been using Motobatt batteries. More expensive, but they get rave reviews, and they are definitely an improvement, but even they've given me hassle- recently my VFR was off the road so I kept the battery topped up off the bike with an optimate. Re-fitted it, bike failed the MOT for a fork seal. Left the bike for 10 days until I could sort it..... dead battery! Completely, utterly unrecoverably, unchargeably lifeless!
And the VFR has a new reg/rec, newly wound stator etc etc. Either I live in the Battery Bermuda Triangle, or marketing forces are at work to make sure we buy more batteries
Also just a note- my Optimate has never recovered a single battery. I've done a lot of reading into lead acid batteries, and desulphating is a complex topic, and there's a lot of snake oil out there. A welder directly connected to the terminals is a pretty effective way to desulphate though