I mixed up MUC and MAD, of course.
I also understand that ZRH will be night-stopper from the summer. So it will be 2 at GLA and EDI each and one each at MAD, ZRH, FRA and LCY (and presumably AMS). Tight, of course, but on the other hand with a fleet of just ten aircraft two spare aircraft will seriously hurt your earnings.
By the way, where do they keep the spare aircraft if they are not undergoing maintenance?