Number of (atomic) actions to perform a task

In all the tools I'm coding, I'm searching the least number of atomic actions to perform a task.

After decades, I came to this empirical conclusion:

I noticed that my likelihood/probability to use any tool (all other things being equal) is more or less proportional to:

   P = 1 / a^2

where a is the number of required actions/user inputs. If the number of required actions is doubled, the likelihood that I'll use the tool is divided by 4.

This is done on a rather empirical way (details about methodology currently being written), but are there some studies about such a law?

I've read The human interface by Jef Raskin (one of the leaders of the Macintosh project) which is quite interesting on this topic, but I'm curious about other references on this topic.