In any software development timeline given, triple it to be safe!
Programmers don’t just pull perfect codes from their butts
Programming languages (yes, in some scenarios, even python) are hell to work with. And yes, I know developer experience has gotten so much better compared to 5 years ago. Still, there are too many unknowns.
It’s like trying to shush a crying baby. Trying every trick on the book to put her back to sleep. But naaah, all she does is cry (no reasons, no hints)
This makes a half-an-hour job take 2 days (hence the unknown delays and setbacks)
If you meet a programmer that pulls a rough prototype of a single module inside a program in a few seconds and works immediately. Know that he/she has 10+ years of experience in that language domain.
i.e. that one granny that “feels the baby” and knows what it wants, making the baby calm immediately.