Good point about roughing the finish...some dipsticks are machined criss-cross for the same reason...Ford Superduty 6.0 drivers often use a black magic marker, which helps on the original dipsticks.
Incidentally the lower of the two lines is the "add oil" line and, between the two lines is the don't bother to add oil area, IMHO. [actually, the lower line is designed to tell you that you can safely add a "unit"--say, a quart--without risk of overfilling]
There are a number of variables like the time it takes the oil to completely drain down to the sump from the top end, which depends on the viscosity (and the cleanliness of the oil which, in turn, affects the viscosity ..as does the temperature ...and the actual volume changes with temp, too) ... It takes a lot of time and patience to be compulsive and get it right to the "don't-add-any-more" line with risk of overfilling (causing frothing and loss of the very lubrication you seek) ...so, unless you are losing/consuming oil at a substantial rate, why bother?