Mate this is a foolproof routine for you r lagging parts, listen up:
For chest:
Start with cable flyes, which means put a bench on the middle of the cable station and use the lower cables and use them instead of the dumbells, its the only way you get stress in the inner part of the peck (that or peck deck machine but i prefer this excercise).
do 3 sets of 10 and hold for a couple of seconds at the top.
As in in one, hold 2 secs and do another one and hold. etc
Then id go for dumbell presses, flat and incline. 3 of 10 each and finish off with a cross over set of 20 reps.
Shoulders:
well separate it from the c hest day if oyu train them together since it may be putting too much stress on the delts and if you are lagging the medial head heres the drill.
Start with a superset of lateral raises (hold two secs each rep) with dumbell presses (vertical, well duh) , again 3 of 10 is the magic number.
And blast them with a final 3 sets of 8 static raises. Well its a pain to do but its surely worth it, its just grabbing a very light dumbell on each hand and mimic a lateral raise but hold it for 8 seconds, and lower it just before the waistline and go up again. Thats one rep, do 8 and rest around 50 secs to 1 min between the 3 sets. By the end of this your medial head must be pretty worked haha. You may have read this last excercise in the BBT.
And for traps use the smith machine for a mimic of barbell shrugs, the thing is you can lean back a bit if its more comfortable to you and prevents you from bouncing the weight up, its also great to superset with front raises.
depends on you.
Grow in peace
Fritz el magnifico!