Power BI is a platform, this means that there are few hard rules, more a significant amount of recommendations. You can find a solution and have it working for years before you realise that it could be done better. The issues you will face is that often time the “doing it better” involves some minor tweaks that if considered from the outset would never have been made.
When you’re creating your ETL scripts it is important to make sure that you do not limit the reuse capability of that data. It is common for people to adopt the “I need this subset of data so that’s all I will bring in”, this often comes from the mistaken view that 100,000 or 1,000,000 rows are an awful lot for Power BI. If you only bring in the data for your team or department however then that is all that can ever be reported upon without building new ETL scripts, this divided strategy will hurt you in the end.
When starting to write DAX this is one of the errors that is looked for as a sign that you’re progressing. Don’t worry if this is something you were thinking about or even if it is something you have done, the main thing is to understand why it is a mistake and make sure it does not continue to happen.
