Masters', taken as a different kind of employment - you don't work for the benefit of others but for your own development.

In other words, take the experience that maximizes your growth, intelligently taken. For example: master the theoretics, yet allocate time to get practical technical experience ("can you do this and that"), and meanwhile build a network with the most worthwhile people you meet...

Don't waste time. Maximize experience in view of what will be useful later. You correctly identified "flexibility".