I would be interested to know if iodine tests are a reliable way to know that all the starch has been converted to sugar.

For instance, is it a good way to know if after 30mn of mash-in all the sugars have been converted? Is there a risk of false negatives? false positives?

Please note that this question is different from [this one](https://homebrew.stackexchange.com/questions/4417/is-the-iodine-test-for-starch-conversion-pointless) because I'm not asking if iodine tests are useful in practice (I do not use it for now and never felt that I had to) but I would rather like to know if they work effectively.