With 2m (144 MHz) Yagi antennas at 10m above ground, one site about 500 ft above sea level, the other only about 6 ft, at 50 miles between us, 40 Watts of SSB at each site, the prediction is pretty close to what we experience on daily skeds.
On a 20 mile path over hilly ground, again on 2m SSB, the actual results are similar to predictions.
Don’t forget the reliability percentage figure, and that the results can be influenced by building clutter, wet foliage and warm air rising over urban areas, etc.
SJ