I've kept the same routine pretty much every day. Only at night, for the most part. Once in a while some instant in the late afternoon, then grog later. For a while in the spring, I was using some very high amounts (up to and exceeding 20Tbs in multiple batches/single session) every night but it really wasn't worth it. It seems like, for me, going over 12-14Tbsp a day greatly enhances the side effects and if I'm not getting where I want to be from 12Tbsp, I'm not going to get there with 20 either. In the past, having stronger root, I usually stayed in the 10-12Tbsp range and going higher wasn't really an option since eventually the unstoppable urge to sleep would kick in (or extreme nausea but fortunately it took little effort to sleep through that as well as the rest of the night).
I hear you on kava during the day, for a long time I drank it by noon, sometimes for breakfast. Now it seems like nighttime is a no brainer.
I've tried taking "heady" varieties during the day and it doesn't really work out well. Only occasionally. near the end of a workday where I have nothing important to do after work. During the kavain buzz it's more enjoyable doing something that I don't like to do but that quickly morphs into an "i don't want to do anything but drink kava and chill" type of attitude and whatever I'm doing just feels like a chore that's killing my buzz. Unlike other herbs, chemicals, kava really seems to demand all of your attention for the best experience.