This is the reply I received from the CNET Download product manager and I hope it clarifies the count:
The "Last week" download count is the number of downloads from the
*previous* week, so if you downloaded the app on Monday and checked back on Tuesday, that count would not update as it's still showing downloads from the prior week.
The total downloads count does update every night, so that's the one you should track.
Let me know if this makes sense.
I've been tracking Wordweb downloads and it reports 31,383 for the week. It had this number on Monday and when I downloaded on Tuesday it didn't even increment to 31,384.
I'm a software developer and am trying to get a feel of market interest in different apps and I would like to trust Download.com for the numbers but with this experiment it shows the site is not keeping accurate numbers and makes me worry that the numbers have nothing to do with actual download activity.