I regret that as a frequent user of MAN, GavinC's comments are more likely to be accurate than someone who has flown from there on the odd occasion and possibly during a period between the low cost departure swarms.
Yes, it can be efficient, but when it is, we look at each other and say 'Why can't it be like this all the time?'
I flew through Luton at 0715 on the Sunday of half term. It was very very busy, but all the security lanes were open and we were through almost without waiting. Why could MAN not do this on the 24th December, when I suffered a one hour wait in line for security.Instead they had three lanes out of 12 open.