Recently on my reactor I had quite a fer of the extension connections give problems. The reason: at 6V some of the Hitec HD female sockets were getting oxidised (incredible as it sounds) so the servos would start reacting late.

I feel that if the connections are in an unaccessible place, solder and then use shrink tubes. Use connectors only for the connection between the aileron servo leads and extension from the receiver which you regularly plug and replug.

I now use the orange safety clips (many have described above) on these connectors. It lets you disconnect quickly if you need to do so. Earlier in my trainer I would tape the assembly. I have never had a connection come off in either case, but there is always a first time and my luck with connectors and servos is not very good recently

Ameyam