I had never practice Combination Sets, but today I read an article about it. It's something I also had on my mind to try. It doesn't save time, but give your muscle more time to recover.
I still do the old approach. That is 3-4 exercises. 3 sets each. I finish one exercise at a time.
With the combination sets you even jump to a different muscle group. It doesn't fit my program but at our age I think variations are good (at any age actually) to avoid stimulating the muscles the same way all the time. One thing is what I think. The science seems to say that combination sets are worth it. What do you say? What are your experience?