- When can a developer take his time?
- What restrictions are there about what can and can’t be done in that time?
- How do people manage their schedules? Should they manage it?
- Is this time should be tracked?
- How is it decided what people can work on?
- How do you stop someone’s project if it’s deemed not useful? Who deems it this? Is there a committee? Peer review?
- How do projects “graduate” from 20% time?
- How is overall success of the program judged? $$? Customer value? Engineer happiness?
- Should developers form a team, or should it be single projects?
But despite all these difficult questions probably it’s worth trying … What do you think?