well let's say that on monday you do bench, and other chest exercises. then on tuesday you come back and do the shoulder press, and other shoulder exercises. the muscle worked the most in those exercises besides chest & shoulders is triceps! and then after that some people will do an arm day and isolate triceps & biceps, so you're actually working them 3 times in 3 days, which is overtraining.
but the workout posted, is generally the one i follow. it is a little to much lifting for some, but i prefer it. it will give your triceps 3 full days to heal, which is enough time for ALMOST everyone(some people need more). i also ensure i get enough protein & sleep to heal 100% before my next workout.
as for spliting up your push routine.. i switch what i begin with every push workout, going from...
shoulder press, bench press, incline
bench press, incline, shoulder press
incline, shoulder press, bench press
~~i do this to ensure i don't go into my shoulder or incline exercise half strength because i always do flat bench first. And i always work from compound>>isolation.