On the contrary, I'm glad he's being consistent. This how it should be done (midnights should count as 0.25 days, Previews 0.5 days).
Theater day is from ~6:00AM - 5:59AM (24 HR)
12:00 AM - 5:59 AM is therefore 6 of 24 hours, so 0.25 days
6/7/8 PM previews are between 10-12 of 24 hours so they should be counted as 0.42-0.50 days. A little rounding is reasonable, but this is the better way to count it, especially for analysis purposes.