Not an expert here, but using the 285-50 ("standard") metal pour spouts, I've
found that a 3-count gets me PRECISELY one ounce (one-onethousand,
two-onethousand, three-onethousand) as long as you truly end your pour at the
end of the last "onethousand" (i.e. anticipate the end and quickly tip your
bottle so the pour ends quickly at the end of the count).
If I need to be precise with 1/2 and 3/4 measurements, I use a jigger.