never been a gm my self have tried several different guild types thou and been officer in a few in my own opinion people have good days and bad days so recruiting more people for the guild would be a good idea or you might have some burn out from the pressure.
an idea is to get as they said higher up a good number do some rotations can be from week to week or fight to fight as said and make sure people who are not focused get replaced let them know before hand that it is okay to ask to be replaced if they feel they can't do the job 100%
make sure to have people on reserve for each raid reward them while they wait they wont mind (dkp /points /repair gold/ possibility's are many) have them be on your voice communication during raid so you can quickly get them in if needed.
seen this used in a few serious raiding guilds and it seems to work and it also seems to keep people happy ofc if someone simply fails every night you might want to replace them in the guild entirely or have a chat with them on what could be wrong this way you would seem like a caring guild leader that will help if needed
you might want to make 2 officer spots 1 officer with only one goal recruitment 1 for sorting the raid list/ rotations and you might want one to sort loot during raids so the raid leader can concentrate on the instructions they give.
sorry think im straying off topic here but i would suggest getting more people and rotate reward the ones on reserve/ bench
If love is an illusion to hell with reality