I'm averaging about 5,000 house of reps tickets a day. Take into account the extra processing and transport of absentee votes, postal votes, pre-poll votes. All votes need to be double counted and sealed before they leave one location, and then double counted when they arrive somewhere else. (First time for me, apparently it's a more stringent protocol since all those senate votes went missing last time in WA).
If you're out by more than 1 or 2 in 5,000, then you need to find out why. They go to extraordinary lengths to account for every single stub that is left from the voting paper dockets. It's impressive (and time consuming!)
Don't get me started on sorting preferences for the monstrous senate paper!