The other day I was showing my husband the TWSBI Eco pen, which I love by the way, that I received from Goulet Pens. He looked at it and said "Why do you need another fountain pen? You can only write with one at a time." I, of course, looked at him like he'd lost his mind and began to tout all the reasons I love each and every one of my 33 pens.
Firstly, every pen in my collection is a different color. I have two bold red pens, a Jinhao 159 in Red and a Monteverde Limonada in Torino Red. The reds are very similar but are not exactly the same and the pens couldn't be much different. The Jinhao is thick and heavy, with a grip diameter of 16mm and a weight of 50 grams. The Limonada is thin and light, with a grip diameter of only 5mm and a weight of 1/2 that of the Jinhao at only 25 grams. I also have two clear pens, a Nemosine Singularity and a TWSBI ECO. But the different workings inside the pens that are revealed by the clear bodies, change the overall look of the pens, as does the colored (or not) caps and grips.
Every pen feels different in my hand. A lot of factors contribute to this of course - weight, diameter, balance, posted or unposted, just to name a few. This makes the writing experience with each pen unique. Even the same manufacturer's models can vary. For example I have three Lamy pens, a Logo in Twilight, a purple Al-Star, and the Safari Special Edition Dark Lilac. The Safari and Al-Star are very similar. But the Safari weighs 10 grams and the Al-Star weighs 12 grams. The Safari's diameter is 12.31mm and the Al-Star's is 12.78. The Logo however, is a completely different stream-lined body and the Safari Dark Lilac has a textured body. So each of these Lamy pens gives me a completely different writing experience.
And then, of course, there's the nib. Every nib has its own characteristics, whether you buy two pens of exactly the same make and model or two completely different pens. Sometimes you get lucky and the pen feels great right out of the gate. But sometimes they need a little tweaking, perhaps a bit of smoothing or shimming to make them write smoother or wetter. Or sometimes you can't get the exact nib you want and have to order a different one separately and swap it out. It's sometimes a journey to get a pen to write exactly the way you like. But that's the beauty of the fountain pen - the ability to make it exactly what you want. The nib can be fine-tuned for your hand, your grip, your angle and your style of writing - making it distinctively yours.
When I started getting interested in fountain pens last November, I never expected to have 33 of them within less than a year. I started with one lonely Cross Classic Century silver fountain pen I had gotten for work about 30 or more years ago. But now, after meeting other like-minded souls, I've learned that 33 is really not that many pens. In our Seattle Pen Club there is one person who has a collection of more than 400 and I'm sure there are others that have just as many or more, I just probably haven't met them yet.
So my answer to the question then is that there are never too many pens. Each pen has its own inimitable look and qualities that make it individual. Even pens with the same body, color and nib can write differently, especially if they've been fine-tuned to write perfectly in the hand of their very individual and unique owner.