Rajul,
I don't use the crayon method. I used the hinge slotting machine on 1/2 of my planes and I really like it. I started drilling the hole for the CA on my last two planes but never did it in the past. I use about 8 drops of CA on each side while flexing the control surface to maximum deflection. I don't wait for one side to dry but imediately turn it over and soak the other side, once the CA dries it won't whick or take anymore CA so you only have one chance to do this step. I do use a pin to make sure the hinge goes into each surface halfway. If I end up with a gap just big enough to slide a piece of paper through it I am satisfied. I don't touch the surface for an hour after I glue it and then just cycle the surface back and forth by hand to loosen the CA on the hingeline. I also buy small bottles of thin CA so it is usually fresh. On sealed surfaces I don't get the iron on the hinge for fear of melting or making it brittle.

These are the things I have done in the past and they have served me well.

The 1/4 scale has about 50 flights.