Man, that's the worst feeling. I started doing the same thing after a similar mess-up, but I make the sim run at like 25% speed now. Watching it move step-by-step catches those little clearance issues you miss at full speed. It's boring, but way cheaper than a new sheet of material.
Ugh, been there. I ruined a whole sheet of acrylic once because I was in a rush and skipped the sim. Now I do exactly what @danielblack said and crawl through it super slow. It feels painful watching it inch along, but spotting one tiny clamp touch or weird move saves so much time and cash. I even leave it running in the background while I do other stuff. That boring check is the best insurance.