I do chest, shoulders and tris on the same day and it works great! but 8 sets for shoulders seem a bit much, take into consideration that the 12 sets for chest will probably hit the delts to, therefore bringing delt work up to 20 sets!
maybe its the gear but i started to do chest and shoulders when i started my cycle and i have noticed that my delts are alot more developed and i have been having people tell me that my shoulders appear broader, so from my opinion i think its a wise choice to do both chest and shoulders on same day
i do chest, shoulders ,and tri's all in one day too. see when u work chest u indirectly work shoulders and triceps and alot of shoulder work will also indirectly hit your triceps. that way those muscle groups have a chance to fully recuperate. its an individual thing and this is whats worked best for me.