these are facts, not fiction.
i definitely wouldn't do a chest/back routine twice a week. it would interefere with your recover. plus you need to put all effort into that one workout. and trust me....u need not focus on only those bodyparts. people also need to focus on their quads and hams in order to look really ''big'' which is probably your goal.
and even if you trained once a week...i have some theories that would
skyrocket your gains( i tried it myself it it worked!)
theory one: for back widthness, only one is best.....freeweight pullups.
yes...they are different from cable pulldowns. think of it this way....what do u think would build more mass....barbell curls or cable curls? yeah that's what i thought. if you can't do your own weight then alot of gyms have the assisted chin/dip machine, which helps you eventually get to your own bodyweight.
theory two: for chest, do you want to have a thick full barrelled looking chest....or a drooopy old man chest? yeah i'd choose the first choice. alot of people do decline and flat bench press.....wrong wrong wrong! that works the lower pecks; which makes it look like your chest is sagging. just imagine the side of your chest if you're lower chest outgrew. gross!
if you want to get a nice full chest, use incline barbell or dumbell presses.
theory three: add pullovers(machine or dumbell) to your chest/back routine. all it takes is only 2 sets of these to work your serratus which makes your chest look more thicker and more bigger/primed up. plus aside from the chest benefit, it isolates your lats so it has a double effect. it's like hitting two birds with one stone. go figure!
those are just my opinions about chest/back. i mean i have a barrelled chest and i can honestly attest to those theories that i mentioned above that made my chest and back the most intimidating bodyparts.