If you boil the butter, sugar, and milk for less
than 1 minute the cookies will not set up properly and will be sticky and wet.
If you boil the butter, sugar, and milk for more
than 1 minute the cookies will end up dry and crumbly.
, if you live in a humid climate, and it is very humid while you are making these cookies, boiling the butter, sugar, and milk for about 1 1/2 minutes is a good idea. The humidity in the air can make the cookies not set up properly as well. I live in Oklahoma and only when it is very very humid or raining outside do I have to boil for 1 1/2 minutes.