Wow, you sure are organized!
I tend to simply clean them whenever I'm changing ink (which is typically very often, so many cool inks out there) or when I know I won't be using a certain pen for a while.
That's an advantage to the converters, a lot quicker to clean. With some of the piston fillers it can take ages, twisting and turning, twisting and turning..... Then letting them rest for a while with water in the reservoir to dissolve any remaining ink, and then start all over again Especially if you've had some heavily saturated ink in there, red inks in particular in my experience.
I just have a bad memory for many things. If it weren't for post-its and phone notifications, I'd wave any resemblance of organization bye bye.
In my experience, the twisting and turning part can be shortened by using warm water. It also helps that I don't demand 110% like-new condition from a used fountain pen when I flush one. Once I see the almost-clear water coming out of the nib, I stop.
Do you do the soaking-in-water-overnight part every time you change inks? What stubborn inks do you use?
Red inks are a delicate topics for me. Pelikan 4001 Red and Diamine Matador have actually been well-behaved, but holy saints, J. Herbin Rouge Hematite is hanging onto the feeds of my pens worse than a haunting ghost. Perhaps I should call an exorcist..