Unfortunately, this is a penny wise pound foolish approach. Every moment we spend warming up will contribute to our playing better. Warming up assures that our muscles are ready for strenuous work. Taking a gentle approach also helps us to do more with a reduced probability of injury from overuse of cold muscles and connective tissue. The warm up improves our flexibility in our hands and arms. If dancers just launched into practice without warming up, they'd be on ice, anti-inflammatory pain relievers, and bandage wraps. We are like dancers. But while they are working large muscles, we use those muscles (albeit differently) AND we use some of our very small muscles. And we don't want to end up on the ice/aspirin regimen, do we?
Warming up is key if you are young or old, new to the harp or expert, in a well heated space or in a freezing rehearsal hall. The things you do to warm up with help you be more flexible and limber and will help you improve your form and tone as you work on the music you so desperately want to practice.
And enjoy this time you set aside for yourself. Know that these “useless” activities are the foundation for the rest of your practice, an investment in your rehearsal time, an insurance that you’ll get to keep playing!