Why Czech's hatching progress increases and decreases??!!
On day is is 99% and next day it becomes 95%???!!!
It is a well known fact that the estimates on the courses page are inaccurate. Just look in the incubator.
Progress is computer generated from data supplied by the course teams. In other words the principles of DIGO prevail :-D i.e. Data In Garbage Out.
Check the incubator page if you are curious about the progress: https://incubator.duolingo.com/courses/cs/en/status
Yes. And once there, avoid getting distracted by the graph and all the ways of extracting 16 insignificant digits from it. Just pay attention to the numbers shown next to "Complete all words" under the graph. At the moment, they are 2122/2234. I bet both will increase by tomorrow.
I've heard the percentage is how many words there are translations for. If they add a bunch of words and haven't translated them yet, the percentage goes down. It just means they're making the tree bigger.