It depends on the church - in some a slick practiced performance a la Hillsongs is what they are going for - in which case having the songs beforehand is kinda a vital way of getting there.
in other churches their approach to “spirit led” might mean the set list is twenty songs and nobody knows exactly what will end up being played. So a lot of thinking on your feet.
ive been in both, both have positives both for learning as a player and also learning as a band.
You know what, I can turn up somewhere, get a chart (or scribble one down) and improvise a baseline on the spot… now while it would be nice to have had the songs beforehand, I’m not sure there’s many other environments where I would have learnt that. Esp in a smaller band where you end up playing a major part it changing a set of chord changes into a song…
im thinking of taking @xgsjx as an example and trying to play without music - which will stretch how I think about playing