[Ian]

Must say the 12 week rule would never work for me. At times one song has great significance for the congregation, and GOd uses that song to speak to peoples hearts. We often sing 'that' song every week for a month! Used to have your struggles, but have now pared things down to a constantly updating repertoire of around 80 numbers, of which around 50 will get most of the play time. Yes, it does make things much easier, and that means for the congregation too.
Music is an aid to worship. The better a song does the job, the more you should use it? No? Stay fresh sure, but lets face it, there are worship songs and there are worship songs!

 

[Ian]

Bradshawm: the more you do this, I believe the less you will be intimidated by a large repertoire. I am sure you will find most extremely simple harmonically speaking. You will be able to improvise without writing parts. It is also OK to play for 3 or 4 of the songs - the ones you feel comfortable on and can really contribute meaningfully - and sit out (or sing!!) the others.
As stated previously though, I am glad I work in an environment of constantly updating, but limited repertoire.