Too many aircraft in one sector? Perhaps the Spanish should look at the southern German sectors. They seem to be about.... oh..... 20NM across and appear to serve no purpose beyond giving employment to German Air Traffic Controllers. You check in, listen to the silence and then a couple of minutes later get handed over to the next sector for a repeat of the same.
Not knocking the German Controllers, just the irritating frequency of change between tiny bits of airspace. Big sigh of relief when you hear "call Maastricht on ...."