In the simple view, the more strands you have, the more surface area you have and the more vapour you can put out.
However...
The more metal you have in the coil, the more power it requires to get it to temperature. A heavy coil needs more power to work; it doesn't work with low power. If you have more power you need to have more liquid flow
through the wick. The design of the coil and the wick, and the atty and the
mod all have to be right. Getting all that correct is a dark art - there are no simple rules to follow, it's all down to experience.
If you get it wrong you will end up with a coil that is too laggy at low powers and burns liquid at high powers, making it functionally useless.