YES. if you are printing multicolor you MUST flash between EVERY color. Because the ink doesnt absorb, wet ink will pull off almost entirely and smear badly if you step on it with another screen. I had a 6-color print that I had to do on these once, and had to setup the revolver to run the aprons around all six times. Didnt get much done that day.
Once all was said and done, I dont recall having any issues with final cure, but you may wanna do a wash test first. The company I worked for at the time wasnt very diligent in this aspect, so I dont know if any issues arose.