When it comes to installing CA hinges, I always fold them in half and make a creased line. I then fold it the other way and crease it again. I push half of the hinge into the moving surface with the hinge folded 90 degrees. The creased line helps keep things aligned correctly.

The hinged surface seems to pivot better with creased CA hinges, i.e., more like a pin hinge. I have not had any hinge failure. I have heard of CA hinge failures especially with 3D planes. Is my practice safe for Giant scale planes? Any comment will be appreciated

2 D, 3 D or 4 D, no problem, but the bigger the airplane the more hinges needed on that same surface, you can even place one next to the other on the ends of the surface, with say, from 1/2 to 1 inch space in between. (to drive a pin through them is a good idea, do it from the bottom and just long enough so as not to come out through the other side, looks better)
If flying the biggies, remember that the vibration transmitted by those gas engines is quite heavy, bending the hinges before installation is fine, remember also that to have the actuating pushrod too close to the surface is also a bad idea, hence the need for larger servos, which can produce more throw, without having to use very long servo arms, bad idea on ailerons.