I live in India and have joined 4-5 gyms in last 4-5 years in different cities. Every time people do and also suggest me to do exercise that target only one muscle per day. e.g. on Monday only biceps exercise, on another day only triceps exercise and shoulder exercise on any other day, i.e. to do exercise that target only one muscle each day.
I exercise in the gym daily for 1 hour in the morning and 30 minutes at night after dinner and before going to bed (most time of the day I just sit on a chair as I'm an IT developer). I want to build or grow muscles mostly on bicep, triceps, shoulder, chest, wings (not abs, back, and leg).
So is it really necessary to do exercise targeting one muscle a day like I mentioned above, and if it is necessary, do I have to do exercise targeting only one muscle at morning and night on the same day, or can I target one muscle at morning and another at night? How much time of rest should one maintain between two different kinds of muscle exercise? Or is this all just a myth?
Also if I do biceps and triceps together then will the benefit of exercise gets reduced?