The more you run, the more likely you are to see the rarer occurrences. As I said above - I've had a few really close calls in my numerous 7-5 attempts.
To give an idea of how many 7-5 runs I've done, I've gathered around 18k sun medals since Tuesday. That means, I've probably run 7-5 around 40 times. I've probably been one turn from losing three times. If things go really poorly for skill activation for me and really great for the pest, I assume I could actually lose. So, does it happen often? No. Can my team struggle? yes. Does it usually? no. But at 1.25m total power, I'd have not expected any close calls.