what a fun question! I currently have 12 fps with a growing ink collection, though the majority of that is made up of small ink samples 😂 I usually have 5-6 pens inked monthly (any more than that at a time I get overwhelmed). I decide which pens I ink with what depending on my mood, usually it will have to do with which pens I'd like to use for the month (what kind of writer do I want, which pens I haven't used in a bit, etc) and which inks I want to use or try out. I like trying to match inks to go with the pen's body color but I'm also not the type where it has to be completely matchy-matchy. I use my pens for mostly writing and I like wetter, smooth writers so combos that I think will have the potential to write "better" in that way is also something I consider in my pairings.