Gaining and losing 6 pounds in a day over multiple days using various methods to include excessive sweating in a sauna doesn't sound healthy. If they don't go back to 10 weights in the Olympics, then perhaps they need to include a hydration test as part of the weigh-ins. It would probably force a lot of in between wrestlers to wrestle up a weight instead of down, but they wouldn't be risking their health and welfare in the process.
All the wrestlers know when the weigh-ins are coming into the tournament. I don't feel sorry for anyone missing weight.