On a rotary mower the heigh numbers mean absolutely nothing
A deck at the same height setting will cut the grass at different heights depending upon the temperature, time of day & season
So 1/2" height adjustments do not mean a 1/2" difference in the height of the grass .
For that sort of precision you need to go to a reel mower which is why reel mowers are used down here for golf greens & some fairways , bowling greens, croquet greens, cricket pitches .
During foot ball finals also on foot ball fields ( all codes ) & tennis courts all year round.