I can do a week's worth of handholding for all the services I run in about 2 hours. Normally I do it during the week as needed, but occasionally I'll troop off into the sticks for up to a week at a time. Thus far I've managed to pull it off without the business collapsing.
I like the idea though.
I really like the idea too, at my last job there was a lot of discussion for a while about taking 4 hours each week to work on whatever you wanted and present it to the group at the next team meeting. It never really panned out, at least not officially.
My thought on this initiative was that it reminded me of the Google system of personal projects, expect coordinated across the entire company.