Yep, exactly. What would extra work do for you, that the base 5x5 workout didn't already do?
Short answer: Probably not all that much once you factor the energy output compared to the results earned.
Or what it you did the 5x5 workout, and then every hour on the hour for the next six hours you did one more set of 5, to really drive home that strength signal to the muscle. Or after 48 hours, do the 5x5 again but use 25% less weight, 30% faster lifting tempo, and 50% less time between sets, to cause an even more unique response in the muscle fibers.
Dude, more training does not always mean more results. As was said, there can be some benefit to doing "more", but it should be done as part of a comprehensive program that takes training frequency, volume, intensity, and recovery all into account. Simply tacking on 1, 2, or 20 extra sets in the hopes of building more strength or muscle is nuts.
5x5 is a time-tested program, perfectly fine as-is. There are other programs that do include things like backoff sets, added volume, feeder workouts, etc., but those are different standalone plans. If you want to experiment on your own, that's cool, but approach it in an organized, methodical way. Have a plan that's at least a couple of months long and know ahead of time how much you're doing on which days of which weeks.