If the charging system is working correctly, you should only need to hook up the battery tender when you're not riding for an extended period of time. Or at least that's my thoughts on the subject. I commute to work on mine whenever the weahter permits and therefore very seldom have to put mine on the charger.
I went on vacation recently and hooked it up then, but that's the only time since I got my charging issues lined out. I was still nervuos after replacing my r/r and would check the battery with a multimeter after every ride, but it's working fine so the battery tender is a not needed luxury for now.
When winter comes around I'm sure that I'll hook it up more often, but I ride in the winter too as long as it's not raining since it very seldom snows in TX and freezing weather is not very common.
I smile 'cause I don't know what the h*ll is going on.