Filling with a syringe is def the easiest and quickest way to fill a carto and I'm sorry lace dolphin, but there's no way that the condom method is less messy than using a syringe. I'm not saying the condom method is bad, bc it's def better and easier than drip filling, but the condom method really only works well with regular size carto. A syringe takes all the guesswork out of filling and ensures they are filled correctly whether it's a regular size carto, an XL carto, or even something like an eGo or Epower mega dual coil which hold upwards of 5-6ml of juice.
I know everyone has their own method that they like, but using a syringe is by far the fastest way to fill a carto and basically eliminates the chance of burning a carto bc you didn't put enough juice in or waiting enough for the juice to settle