I've seen this tried in a few ways that didn't really work out and one that worked well: (edit - this is always highly dependent on the people and small differences, this is only my experience of 10/20% time that I've actually participated in and the issues that appeared at my workplace)<p># One day a week:<p>Cons: people are off more on fridays, feel like they're missing out. Some things need more than one day, other priorities pop up a lot on fridays. Hard to force people to suddenly switch for one day.<p>Pros: Simple, everyone gets time together. Easier to actually 'enforce' and not see it just disappear.<p># One week/similar per longer time period:<p>Cons: Lots of time to stop everyone working, doesn't line up with all schedules, etc.<p>Pros: Longer to do things, everyone available together. Same pros as one day per week.<p># Organise it yourself, completely freestyle<p>Cons: People don't actually do it most of the time, seems like they're taking time away from their main project.<p>Pros: Timing issues pretty much disappear, but things can always be put off. Easy for it to just be forgotten.<p>-----<p>The way I've seen it work well had these properties:<p>No fixed time or schedule, you booked off time to work on what you wanted.<p>Your manager can't indefinitely say "no", but if you're trying to book off the day of a release when you're planning a big release then they'd ask you to wait a bit.<p>To get it you have to say what it was you wanted to do, but this only needed to be a brief sentence on a wiki somewhere (could be "play around with X" or "try and make a Y"). You also needed to say if there was anything you required, and they'd help you sort this out.<p>The time is considered like holiday. You don't pull in workers from holiday to help out, you can't pull them away from the time they'd requested for the project.<p>You were encouraged to go and work in a different building/office if you wanted so you're not surrounded by people asking "quick questions".<p>You were required to put any code in a particular place.<p>You needed to briefly say how it went.<p>You had to be reasonably willing to say what you did in the next all-hands.<p>This was all fairly lightweight, booking time off wasn't a difficult thing and getting approval was just a quick chat about what you were planning. You could grab a few days or an afternoon, and they'd help out if you needed other equipment/etc.<p>Overall I think what will work varies massively on your workers and current workplace, it's vital to try a few different things and tweak as you go.