This has worked great for me. Even with a mostly dry carto I can usually only get 10-15 drops in before it won't soak down anymore. Before, I would rotate
through 3-4 refilled carts while at work and usually
vape at least 2 of them dry. I refilled my 4 'work' carts yesterday with this method, rotated
through just 3 of them and didn't dry any of them out.
One thing I've found I need to be careful on, after spinning, the top can still look really dry but be almost full, making it easy to overfill. I've started poking around with a paperclip after the second spin to see if there's liquid close to the top.