Thanks for the input thus far. Now that I'm beginning to acquire a few more pens, I'm thinking that I should only keep a few inked up at any given time. I want to keep at least 2 or 3 inked up so that I can have a backup if I'm out on the go and one of them dries up or runs out of ink.
I normally have 2 inked up. One is whatever pen I am currently using. The second pen Visconti Rembrandt eco ball for times when I am unable to use a fountain pen. Currently I have MB blue in the Visconti and Pelikan brown in a Waterman Cerene.
Usually two. One with blue ink and one with green ink. Right now that's a TWISBI 580-AL with a fine PB stub nib and a Lamy 2000 with a medium PB stub nib. A 51 Vac fine point is next up.
Right now I have 3 inked up, and a Montblanc rollerball. When I finish the 1, I won't reink it for a while. I will keep one black, one green and the montblanc is blue.
I have quite a few. I had a lot of samples and filled as many pens as I could to get through the samples. Now that I'm narrowing things down to what I like and don't, I'm just trying to write dry as many of the pens as I can to figure out which of the pens I want to keep in a consistent rotation. That's been a tough one. Think I'm hovering around 8 fountain pens and three rollerball pens. Two Mont Blancs, four TWSBI, a Pilot Fermo, and a Sheaffer No-Nonsense. For rollers, there's two Karas Kustoms Bolts and a Karas Kustoms Retract. Somehow, I manage to use all of them fairly regularly.
I try to keep 4-8 pens inked at all times. At least half of those with be works loaded with blue or blue-blacks inks for work and the remaining pens are loaded with whatever colors I fancy for personal use.
Lately, I've been only keeping 2 or 3 inked up at one time. I start to lose track of my pens if I keep anymore than 4 or 5 inked up. Plus, I'm finding that I'm more apt to cleaning the pens in a timely manner if I'm not having to take a few hours cleaning a bunch of pens. Or, letting some pens sit there with dried up ink in them until the rest of my inked pens are ready to be cleaned.
Currently sitting at 9, although I've had 12 inked at times. I was up to 11 last week, but I decided to drop a couple of fines rather than refill. Plain nibs get boring.
Bare minimum I keep inked is 6, a pair of fine & medium demi 51s, an old style M200 medium, a F-C Model 02 with a steel broad SIG, a F-C Model 40 with a steel Masuyama broad stub, & a Scriptorium custom with a steel Masuyama broad italic.
I currently have one inked. I seem to mostly use my pens one at a time. Sometimes I also ink up a visconti roller ball that I use for things when I can't use a fountain pen.