If your "going rogue" project fails, then you can be seen as not having done any work for X weeks. If your manager was against you working on that project--espe

If your "going rogue" project fails, then you can be seen as not having done any work for X weeks. If your manager was against you working on that project--especially if they needed you to work on something else--then you will be seen poorly, and that can be rough for your career.