Distorted Rhythm- I use the bridge pickup
Clean- Both
Lead- Neck usally with a bit of chorus
I'm a death metal player so i dont use cleans much but when i do i like using both pick up so it dont sound thick and muffley and still got a little bit but not so much it makes it harsh sounding
and well IMO the bridge is the best pick up for aggressive death metal sound
and with lead i find the bridge scratchy i like the creamy think sounding lead of the neck pick up especially with a bit of chorus

(i can shred for hours with the neck pick up of my blacktop tele and a bit of chorus i love the sound)