Hippy,'M' have been playing the fiddle factor game with regard to manpower for years in the Line Maint Dept. It all started way back with BG, but doesn't seem to have improved with his departure. I seem to recall that the equation used was 3 men per shift for the first 4 aircraft. Any increses in aircraft were met with an increase in labour, but not 1 for 1. If you went to 5 a/c you got 1 more guy, but then had to wait for 2more a/c before getting another man.
Although it is difficult to do because as you stated you do the o/t to help friends in the hope that they will help you, the best thing is to limit o/t, with pressure applied to those who revel in an 80 hour week.
If you feel that your shift becomes harder because nobody is on o/t, remember this:
Your shift is only 12 hours long, only so much can be done by 3 men in 12 hours. The biggest way to make your mark under such circumstances is to make sure at least 1 goes out late in the morning.Do you have 3rd party work at your station? If so a late departure on their aircraft will probably have more effect than one of your own, although I do know that the airline managers are quite regularly beating the engineering managements head about manning levels, so a delay for that reason may help.