Question: do sets need to be completed in a row?
Answer: They don't have to be in a row. You can do Ax3 Bx3 Cx3 or A+B+C A+B+C A+B+C. It's not bad or less efficient as long as you do each with proper form and rest. It would be less efficient if you try to do each exercise as fast as possible and lose your form in the process.