Like Supremor says there an issue with relaxation. I understand that it could be quicker to stretch two parts of thew body at the same time, although in my opinion it is better if everything is carried out properly.
Saying this it is possible to do so, although I would advise just spending a little less time on each stretch so that you can fit in the other stretches.
The main issue being able to relax. Like Supremor says this is important and imagine trying to do a PNF stretch whilst trying to do a wrist stretch. Although this is just my opinion and many others may have different views on the matter.