AppleScript has been the absolute saviour for me on multiple occasions, the amount of scripts I have that trigger at the click of one button is getting to be a bit outrageous.
So for instance I will have a button on my switch control on-screen keyboard, and when it's pressed it sends a request To If This Than That, which communicates with my LIFX lightbulbs and flashes all of them in the house blue notifying my carer that I need assistance. That's just one of many. I love AppleScript.
To be clear I control my computer with my right index finger which gives me left mouse click, a small reflective doton my glasses which gives the cursor movement and voice dictation software which enables you to leave comments on Hacker News.
Pretty much anything used to drive a UI on OS X is going through the accessibility APIs to do so.