Publisher numbers are artificially kept higher than in the past. for example: Sick and Elderly publishers can report 15 minutes and are pressured to do so. Both parents can count 4 hours a months for family study, regardless if it happens or not...after all they take them to the hall, pray at mealtimes, etc.
Also, it be noted that the elders will generally put one hour on your report if you fail to hand it in. This way you do not become irregular/inactive that easy and they don’t have to explain to the CO when he visits. I have seen this on my own report.
Then the focus shifted from average to peak publishers.
So, at all levels there is some number fudging - individuals, parents, elders...and I am sure this continues going up the ladder. And as commented before, they lie about everything else, why not about the numbers.