Each pen carries enough ink to write a 4 to 5 km long continuous line. Assuming that someone writes with 1 to 2 meters of ink every day for 365 days, the pen will last seven years. This is quite remarkable, and refills are quite cheaply priced if you need to purchase one.
The lifetime of any writing instrument is dependent on how much it is used. The more it is used, the faster it will wear out. There are several factors that affect the life of a pen, such as quality of material, construction, how it is made, etc.
Writing instruments are manufactured using different materials. Some materials may wear out faster than others. For example, plastic pens will usually wear out before metal ones because they tend to break down at the interface between the plastic body and the ink cartridge.
In addition to this, there are different methods of manufacturing pens. Some companies choose to use cheaper materials in their products, while others go for quality over quantity. Even within one company, different executives may have different priorities when it comes to design. For example, someone may want company logos all over their pen, even though these make the pen harder to find. This is also true of colors: some manufacturers offer only black or only blue pens, whereas others will also sell red, green or other colored pens.
At the end of its life, your pen will probably not function properly anymore.
Even if you use them on a regular basis When it comes to the writing capacity of each refill, a fountain pen refill will last approximately a day, a rollerball pen refill will last about a week, and a ballpen refill will last around a month. In all of the above examples, I used Parker ballpoint pens and fountain pens on a daily basis. The quality of each pen was excellent. I never had any problems with either type of pen, except that the ink sometimes dried out after several months.
As for how long they can write before they need replacing, that depends on how much you write with them. If you write only a few paragraphs every day then you should be able to use these pens for quite some time. However, if you write essays or books there will come a time when they will fail because the ink cartridge won't hold enough pressure to properly write on paper. Of course instead you could always use a mechanical pencil or digital pen.
The lifetime of a Parker pen is usually between 3-5 years, depending on how much you write with them. After about three years, the nibs start to wear out so you should get yourself some new ones. Also, there's a small metal piece in the bottom of each cartridge case that functions as a sort of plunger to push the ink up into the pen. Over time this piece can become worn down which will prevent the pen from working correctly.
Each pen lasted around 2-3 months, which equates to about 50 pages of notes. The most significant disadvantage was the spotlight. No matter how long you wait for the ink to dry, a highlighter will smear the letters to the point that they are practically unreadable. The other major drawback is the cost: a set of 6 pens costs as much as $60.
What happened to Muji's original pen design? After several successful introductions, including one in 1983 called "The Writer," Muji abandoned its plastic pen model in favor of stainless steel. But despite the change in material, the company continued to make improvements on its original design. For example, it added an angled tip and wider barrel to the "Writer."
However, due to the price of these new models, many customers complained about the expense. So in 1990, Muji released a lower-cost version called "The Globe." This pen featured a transparent plastic barrel through which you could see your handwriting. However, instead of a flat writing surface like "The Writer" had, the "Globe" used a globe-shaped tip to give your notes a three-dimensional look. It also included a metal clip so you could attach it to your shirt pocket or bag.
Unfortunately, the "Globe" only sold for about $10 and went out of production after one year.