All of the above: i.e., no matter whether you make it yourself,or buy it commercially, you have to trim a tab to fit your fingers; Also, as moebow said, it takes far more than a 'few' shooting sessions for a tab or glove, or any other new piece of equipment, to start to feel comfortable and natural to use.
As for choice of glove or tab, I've used them both, and have settled on a tab for the following reasons: As moebow said, shooting with bare fingers will not give you the consistent, smooth release obtainable with a glove or tab. However, with one exception, the gloves I've used, have, over time, conformed to the shape of my fingers, meaning that a deep groove formed at the joint of my fingers. While I could still get a better release with the glove than with bare fingers, the release was not as 'seamless' as that achievable with a tab, due to that groove. Granted, there are some gloves out there with reinforced finger areas that don't allow the groove to form; and I've tried them. The problem I had with those very hard, stiff fingered gloves, was that they changed the position of my hand on my face, because I could not get my fingers all the way to the very end of the glove. So, while the tips of the glove were anchored at the same spot on my face, my fingers were not. So, I would recommend a tab over a glove, but either will definitely give a smoother release than bare fingers.
Oh, BTW, I've never seen a FITA shooter using anything but a tab!