I had to do the accidental yo correction very recently. That time I was sure the extra yarn was going to be too much to work into the other stitches but it was just fine.
One thing that will cause a hole in knitting and I feel it really should be ripped back to fix is when you lay your knitting down and then pick it up and go the wrong way. I still do it on occasion, and I hate to admit it.
I should never overestimate my basic arithmetic skills.