Personally, my routine involves doing triceps and chest on the same day. I know other people like doing other splits, with chest and triceps being done on different days.
for example, lets say 'Joe' has the following routine (lets not worry about legs for now)
monday: chest and back
tuesday: triceps and biceps
on which day would you do bench pressing, if you wanted to do it? or do people with this type of routine not bench press, but use isolation exercises?