There is a lot of variation between cartos, regulars and premiums. I can usually get 20 drops (2/3 of a condom cap, about 1ml) into blanks or refilling using CCRM, even without the Taryn spin; these I consider "normal" or "as advertised" cartos. Tonight I refilled 5 premium watermelon carts, and could only get about 10 -12 drops in no matter what I tried, including spin - all were the same (also note I didn't like their prefilled factory performance, didn't last long and turned harsh rather quickly). I also refilled 10 grape and 5 wintergreen premium cartos, no problem with 20 drops, didn't even squeeze through the batt end hole. I don't try to get more in after spinning, 20 drops is great for me. It is trial and error, I have seen good and bad prefilled and blanks; as a result, don't assume all regular and all premium cartos are self-consistent.
I have about 4 different containers I sort the used cartos into: 1. Good standard carts, 2. Lame standard carts that either don't last very long or tend to burn hot and harsh, 3. Good premium carts, and 4. Lame premium carts. Containers 1 and 3 get refilled 4 or 5 times with CCRM, until I get to the point where I am ready to make a big pot of carto soup; then I boil them all and start over.
Edit: When refilling after boiling, I use a syringe and fill with 1ml per my previously posted procedure since I already have the mouthpiece caps off.