The ball at the tip is designed to act as a cap that prevents air from passing through. However, air can still enter the pen, especially if the pen is not plugged. More often than not, however, people assume that the pens have dried up because they stop writing. Generally, pens last 1 to 2 years before drying out indefinitely, although some can last up to 10 years without problems.
Once again, it's about how they were stored and you can decide how often you want to use your pen without any consequences to worry about. The main culprit is the evaporation of the solvent from the ink, so you should do everything possible to prevent air from coming into contact with the ink. This is less of a problem with the thick, oily ink in pens than with the water-based inks in round-tip pens and gel pens. Whether you have another pen that you use more often or you just don't write much, you might be wondering if you should use more pens.
However, keep in mind that pens can't always be saved, so you may need to replace the pen or cartridge if these tricks don't work. This allows the ink to remain on the tip of the pen at all times and makes it come out more easily when you finally want to use that pen. This may seem obvious, but many people forget to put the cap back on their pens or don't put it on at all, and this greatly contributes to the pens drying out.