How fast can your unborn baby run when he/she is 6 years or say 18 years old? You see the problem with the question? Plants have different phenotypes and traits. Its just a guideline since plants are not all the same and you will find data and charts all over the internet stating different numbers and light distances from the canopy.
It's just a guideline, not a measure hence not accurate. Start with the light high and dimmed and increase as the plant matures. Forcing to much light, especially in veg is very contra productive. For both the plants and electrical bill.