Placing drummers centre stage is standard as the kit takes up quite a lot of space and usually makes the stage appear balanced by being central, and it also provides a more even spread of the drum sound in all directions for the band, and in the case of smaller venues, for the front of house mix.
Since the mid 90’s and performing as Jansen/Barbieri/Karn I would use additional equipment, (pads or keyboards & laptop) on my left side, so I would often be turning that way, and on occasion standing to play, which would mean that I would be facing sideways off stage with my back to half the band. By positioning on the right side of the stage (aka ‘stage left’ for the musicians) and facing across stage I could maintain eye contact with the band when at the drums or at the keyboard/pad. Also, when you’ve got a grand piano on stage, (as was the case when I toured with Ryuichi Sakamoto in 2005, David Sylvian in 2007 and Exit North last year) they take up a similar amount of space therefore you have the option to offset them at angles to one another off-centre. I think it’s nice if you can form the band in as much of a semi-circle as possible if the stage depth permits. The Exit North stage at Billboard in Japan was a tight squeeze as we had a quartet too and there wasn’t much stage depth to work with.