Process is not a substitute for skill.
A methodology's weight is a product of its size and ceremony.
The best way to get a project done faster is to start sooner
If you have unskilled people who work poorly together, no amount of process will save your projects.
If you find that your organization can't make the hard decisions that Scrum demands, then high-risk, uncertain projects have very little probability of success in your organization.
Simple rules guide innovative, intelligent responses. Comprehensive rules guide rote, routine responses.