There wasn't a spot for it, so I voted 'occasionally', but I print about a quarter to half of what I do in monochrome. I usually do a duo/tri-tone to warm it up a bit. Also to correct the blue-green quality that my el-cheapo* printer gives. I fade a strictly b&w layer over the toned layer to get just the degree of warming I want, and it works well.
* Epson 820