How long for changes to Desktop Preferences Packages to take effect?

I set up a Desktop Preferences Package and deployed it to a test group. No complaints. I rolled it out wider and got a few complaints that the connection seemed slow and that the desktop image was missing. Checked the Preference Package and I had mistakenly set the color depth and background image settings. (these are just easy examples that you can see when you log into the hosts)

I changed the settings and rebooted the hosts. No change. I removed the computers from the package and rebooted the hosts. No change. 

I suppose it just takes some time for this to take effect? Is it known how long it takes for these settings to take effect?