Digital photographers tend to produce large amounts of material quite quickly that multiply again when they are turned into different versions (e.g., color and black-and-white). Fortunately, digital data management systems offer practical and efficient ways to deal with large amounts of data. They are only really effective if you use a well-conceived concept for rating, grouping, tagging, naming, and storing your images.
Last but not least, you will need a comprehensive and reliable backup system that covers your new images, your processed images, your image database (if you use one), your applications, and the operating system(s) of your workspace computer(s). For digital photographers without an IT background, backup is not a trivial activity!
Data management is not really a phase of its own, but is in constant use within multiple phases (mainly 2 to 4) of the overall workflow. It is nevertheless practical to consider data management as a separate topic. It is useful to devote some extra time every now and again to sorting and consolidating your stock of images and making sure that your image metadata (and your backups) are up-to-date and in good shape.
You can also usefully spend a rainy weekend throwing out old material, or photos that no longer fulfill your demands or that were only intermediate results anyway (such as print files made for a printer you no longer own). The larger your collection of images becomes, the more likely you will split it into manageable sections in order to preserve performance on a day-to-day basis, or simply to make archiving easier. These are all dull but (in the long term) necessary parts of the overall workflow.
Remember to flag files that you think you will delete some day – this makes finding them easier when you finally get around to them.
Whether you count calibrating your monitor or creating print profiles as part of the workflow or not, these are jobs that still have to be done! They can be time-consuming tasks if you purchase a new monitor or printer.