IMO, outside of freak things happening, such as what was talked about previously, if my personal dog has to handle on Jr single I don't want the ribbon. I wont even to attempt to handle to another mark I'll rope the dog and donate. Now if you desperately want that ribbon. Get in there and fight and let the judges make the decision. IMO if you have to handle to more than one mark in Senior you just did junior work and didn't make the cut for senior.
Now there are extenuating circumstances but if every other dog is killing the test and you are handling you may need to spend more time throwing marks and less time running tests. In no way am I pointing fingers at anyone in this thread. Just giving you what is going through my head when I am on the line watching my dogs run. Everyone is different. I don't like getting ribbons for what I think is sloppy work out of a dog I know is better than that.