No there is no need to build many.
We built one that has two text variables and two bool variables to monitor.
You could also add number inputs and you could also scale it to three or four inputs each.
You can then use one or all of the inputs of the widget.
The Event output is something like
Event fired: ChangeDetected "Text 2 from "a" to "abc"
You can add this single widget several times on your step and apply different variables to monitor.
So there is no need to built more than one change detector to achieve this.
You can find a simple preview here:
Headless Change Detector - Custom Widgets - Tulip Community