Wow. I'm only rotating like 3 cartos. I have about 10 but only use about three at a time. Sounds like I need more. Do you have a fave carto? I'm constantly refilling them. The minute I feel that they are dryish, I open them and wet them pretty well. I do have a tendancy to overfill tho. Well, after a while of using a carto, when I open it up, there is more of the atty visible each time. Like the filler is shrinking to the bottom or something. I have had to reposition the atty a few times b/c it was getting really hot and that seemed to help with the overheating, but nothing I can figure out is causing the shrinking of the filler.
I rotate at least 15 and usually more than that, because I refill at least 12 cartos every day (one every hour, or two every two hours when I'm using and rotating two eGos at the same time. I even vaped both of them at the same time, one on each side of my mouth about an hour ago...it was kinda fun). I like to let newly-refilled cartos set for 24 hours, because they vape much better when they sit for that long, since that allows a longer time for the liquid to soak into the filter and create air pockets or whatever it does to create a better air flow.
Also, it sounds like you're overfilling them, and that will cause the filler to shrink slowly and will cause harder draws, plus a gurgling sound sometimes. The filler needs air to be able to flow through it in order to have light draws and a better overall vaping experience.
I rarely overfill a carto anymore, because I finally came up with this system: I drip 12 to 16 drops directly into the filler when I refill a carto--first, 12 drops all in one spot into the filler (so the liquid will drain into the filler quicker), holding the carto at a 45-degree angle, and then set the carto on a kleenex threaded-end down. A few seconds later, drip about 4 more drops into the filler, set it down on the kleenex again threaded-end down. At that point, there will usually be a spot of liquid on the kleenex at the threaded end within a few seconds. Then I know it's full enough. Then I'll usually blow once lightly into the mouth end (to make sure there's no gurgling inside, which would mean there's too much liquid in there), wipe off the threaded end, and it's done. That refilled carto goes at the back of my rotation line to be vaped in 24 hours or more.
During my first month, I spent all kinds of time messing with repositioning the filler using a paper clip, using a condom to refill cartos, cleaning up lots of messes, experimenting with how much liquid to put into the carto when refilling, and so forth. But I finally came up with the system in the above paragraph, and it works great. I no longer have any messes to clean up, overfilled cartos, or hard draws.
My friend, who just started vaping about 10 days ago, is rotating two cartos. She has 8 more that she hasn't opened yet. But that's fine for her, because she only goes through about one each day. She might start on the second one in the evening, but she doesn't vape constantly like you and I do.
Anyway, good luck. I hope I've helped in some way!