Is it a yes or a no for Multitasking?

Either you are one or you are not. If you know where you belong to, experience says you better stick to the lane. Some people can be very good at multi-tasking or some can only work in a one-after the other approach. Both has its own benefits and disadvantages. The success of your approach lies in understanding what your inherent strengths and weaknesses and using that understanding to decide which would be your best option.