FALLING vs RISING in attachInterrupt function

Projects General Guidance
1

I'm designing an engine rpm sensor/arduino interface for an interim development step to a larger project. I have a non-latching hall-effect sensor less than 1 cm from a small magnet super-glued to the exposed crankshaft pulley. The circuit is similar to the attached image (which I copied from another posting on this forum). I do plan to use a 10Kohm pull-up resistor. The hall-effect sensor is an NPN normally open circuit. I've read the reference on attachInterrupt.
https://www.arduino.cc/en/Reference/AttachInterrupt
So, I'm reasoning that I want to use: attachInterrupt(0, rotCounter, FALLING) since the circuit closes when the magnet sweeps by the sensor and the pull-up resistor and pin connection no.2 are grounded (i.e. falling). But maybe I'm wrong. Please confirm that FALLING is correct or if RISING is correct then explain why.

thanks much!

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2

Usually it does not matter if all you want to do is time revolutions.

Trying both options separately is a good way to find out if there is a difference.

Have you the option of turning the crankshaft slowly by hand (with a large spanner?) so that you can see exactly when the sensor is triggered?

...R