In the old curriculum the labs were also given as packet tracer activities. I used to have my students do them in packet tracer before going into the lab to save time. Since my classes are limited to 75mins. it is hard to do a lab if the students have not first read the lab directions and practiced the commands in packet tracer. If they do the practice first and answer the questions in the handout, then when they do the lab on real routers and switches it takes them less time and they can finish a lab within my 75 min. class period. Right now I have them do the lab in packet tracer from scratch first. My classroom only has 6 switches and 6 routers so with a class of 12-15 students it usually takes 2-4 class periods to complete one lab.