When I say “invest,” of course I mean time and energy. The first answer is, as much as you feel like. The second answer is, as much as makes sense. This advice holds true for any business professional, but is particularly useful if you are engaged in a project like creating a useful database application that can save time: be sure the cost/benefit works out in the right direction. If you are making $60K per year as a program manager, and you begin to focus more on creating a database to help your team save time, make sure you’re still giving your company $60K worth of effort. If you can justify the solution you are creating into the $60K, and many times you can, then proceed, my friend. But if you find yourself spending more and more time learning VB or SQL, and less time successfully delivering on Job Requirements A through Z, no one will benefit.
I’d recommend you do the following, really for any professional project you undertake, but especially one that doesn’t fit your “core responsibilities”:
Get your manager’s buy-in
Realistically evaluate what it may take to get to the end product. As a beginning, this will be hard to do without a solid amount of experience, so figure in between two to six months to be pessimistically generous.
Realistically evaluate what benefit you and your organization will get from the end product. If (3) is less than (2), you’d best do the project on your own time.
Sell the value upwards. Make sure what you create, including a return on investment figure, is publicized to your manager. Don’t assume your manager will see the value without some help, smart as they may be.
The upshot is, make sure you focus on your core responsibilities, and don’t let a project take on a life of it’s own to the detriment of your career. Do you have experiences related to this to share?