Yea and then you use “not” with a variable name that does not make it obvious that it is a list and another person who reads the code thinks it is a bool. Hell a couple of months later you yourself wont even understand that it is a list. You should not sacrifice code readability for over optimization, this is phyton after all I don’t think list lengths will be your bottle neck.

Strongly disagree that not x implies to programmers that x is a bool.

well it does not imply directly per se since you can “not” many things but I feel like my first assumption would be it is used in a bool context

You can make that assumption at your own peril.