I normally do not use tubes for the servo leads.

I connect the leads and use a piece of electrical tape to insure they don't separate. For removing/replacing the leads, just tie a cord on the end of the wire, and as you remove the servo and lead, it will pull through the wing. Tape the cord in place and when you are ready tie one edn of the cord to the lead and pull it back through.

I have not had any problems with the connections coming loose or strain on the leads (I do leave a little slack on them ).

Resoldering long leads has many good points to it, the primary one is there is one less connection you have to worry about for oxidation/corrosion. The downside may be finding the necessary parts to assemble the ends (You could always cut down 36" servo leads to the length needed and not have to worry about the ends ).

In any case, a servo lead up to 12" long the standard servo lead will be OK. A servo lead over 12" long I highly recommend using using a heavy duty lead to minimize voltage drop due to the smaller wire size of a standard servo lead.