I'd be concerned, though, that having an "innovation week" only once every 2 months might slow down whatever momentum you were building on a project. I know I'd want to keep plugging on my 12.5% project after hours in between the chances the company gave to work on it. Which might be exactly what they're hoping for, I suppose.
In our experience it's worked out well, the higher levels of energy and passion seem to make up for the time we spend - and produce some exciting features/products to boot.
You also do a demo. So it's sort of like what they do, but people individually schedule their own at random times, up to four times a year.
I recently highlighted that I'd like to have a pot of opensource days that I could use at my discretion (http://imperialwicket.com/how-about-some-open-source-days). I think it offers a similar benefit, while maintaining a lot of personal responsibility for timing and usage. That said, the structure of WOW week has a lot of built-in benefits as well (team-building, motivation that comes with working as a larger unit, etc.).
Nice job, PatientsLikeMe. It's good that this type of insight is being pushed and highlighted as a productive technique both for the organization and the employee.
Glad you guys are able to do it, and I hope you'll continue to do so as you grow.
We rotate one person on 2-week interrupt-driven bug duty - we do have bugs we have to address immediately, but the interruptions are constrained to one victim. This helps protect the rest of the team.
We also struggle with bleed-over and follow-up work from a previous development sprint when WOW Week comes right afterward. There's no silver bullet to prevent this, though we try to be more disciplined about letting work slip if it can't ship completely on time.