Now I'm hardly using mine (WFH full time, so no commuting for months), I do the same as Paul. Leave it alone, and maybe once every couple of months when I remember I'll connect the tender up and unplug it a day or so later. I don't think batteries really like being charged *all* the time, even if the blurb on the charger says otherwise.
I took it out for a spin a few nights ago (went down to Dungeness and ate fish and chips on the beach - crystal clear evening, to the point I could just see bits of France over the water. Completely forgot to take any pics for a Ride Out thread though). First ride in almost 3 months and (yet again) it just fired right up, first push of the button.
I'm on my second battery - got a whisker under 60k on the clock now, and it's almost 7 years old. Regular use, and periodic use of the tender when you're not riding often seems to be the trick.