Should we consider the time complexity of inbuilt functions and operations

Question

Say I have a list and what to find an element:

I could do this:

if element in list:
..........

Or I could write my own binary search function:
So how do I know the time complexity of (in)

Answer 1

Every algorithm has its own time complexity.
But here is one of many websites that tell you time complexity of the most common algorithms:

https://www.bigocheatsheet.com/

Answer 2

Time complexity of "element in list" is O(n) as it is just a linear search...
(you could also know its just a linear search as it works with unsorted lists too)..

So if you want your code to operate quicker, you might consider making your own binary search function.

Answer 3

Aleksei Radchenkov is there a website where I can find a list of the time complexities