We were taught that you CAN pinch with SQ if you want, but it's not necessary...
We were also taught to do Z-track with IMs, no pinching, but pull the skin back, keep it pulled back until you've aspirated, injected, and taken the needle out. It helps with the med absorption...I haven't seen anyone do it at the dr's office, or hospital, but you know nursing school-they want us to do it the BEST way