Apple used to recommend a complete discharge occasionally but I am not sure they do anymore. There even used to be a place in the settings that would show battery cycles. I still do a complete discharge every couple of weeks.
I don't worry about it, other than running it dead every few months to let it calibrate the battery health. Other than that, I recharge when I think about it. This on a 1st gen iPad, which is still going strong.
I run mine down to 9-10% often and recharge over night been doing that for years and no problem mind you my iPad is the first model and my daughter' iPad mini does the same run it down. Just be sure to turn on Battery Usage on.
Don't keep it plugged in if you're using it for long periods like watching movies all day. It will discharge, recharge constantly, causing the battery to heat up