Do streak freezes only work for 24 hours or two days? I first had a 10 day streak, and got a lingot, but because i then didn't practice for the weekend, I had 0 again. How long do streak freezes work?
This is correct. Once you buy a streak freeze it lasts forever as long as you are meeting your daily goal every day without fail.
The first day you do not meet your daily goal, the freeze is automatically used (you don't have to do anything to cause it to be used) but then it is gone and if you miss your daily goal a second time without purchasing a new streak freeze, your streak will be set back to zero.
They're an insurance. Once you buy one, it will stay there until it gets triggered, and the way it's triggered is by spending a whole day without meeting your daily goal.
For example, if midnight passes and you didn't practice, the Streak Freeze is activated and therefore spent. You have to buy a new one. In my case I bought a Streak Freeze months ago, but because I have practiced every day it is still there, but if, say, tomorrow I didn't practice during the whole day, it would be activated at midnight between tomorrow and the day after... serving its purpose as an insurance by freezing the streak.