Period Measurement of Hall Sensor for Motor speed measurement

I am using the STM32 not SimpleFOC, in the documentation to measure the hall sensor period measurement it uses the concept of prescaler increment and decrement.

My question is i see a pre scaler change of only 1 from 30 to 29 in case of decrement and from 30 to 31 again only 1. Is this sufficient or based on requirement it can still be more?
Few other queries if i check the source code

/* Adjustment factor: minimum measurable speed is x time less than the minimum
reliable speed */
hMinReliableElSpeedUnit /= 4U;

/* Adjustment factor: maximum measurable speed is x time greater than the
maximum reliable speed */
hMaxReliableElSpeedUnit *= 2U;

What are these minimum and maximum measurable speeds? I am not following it. Please advise.

This will be a question more for the STM32 forums, I think…

But I would advise you to use some pre-made driver for HallSensors, like in the SimpleFOC library. Writing the driver yourself based on STM32 timers will be possible, I’m sure, but it will be a challenge.