Agree and very good point.
OP has to decide what they are actually doing. Are they "tuning" the feedline or tuning the antenna?
If the feedline is designed to radiate, IE G5RV on the frequency it was designed to be used on, the feedline does radiate. Some ops like to use certain lengths of ladderline to "feed" their loops as it makes it easier for the antenna coupler to "tune" the antenna or match impedance.
Basic rule of thumb, cut a half wavelength of coax velocity factor figured in, tune your antenna as the analyzer or swr bridge will not "see" the coax if it is an electrical half wave length, this method is almost certain to allow the op to "tune" his antenna and not his feedline.
Then there is always the ground effect to figure in. If you tune your antenna at 9' off the ground then install it at 70' on the tower, Your VSWR will change, the antenna is no longer coupling to the earth.
Lowband HF antennas installed close to the ground have great broadband width, due to the coupling to earth ground. Get that antenna .25 wl in the air and it will change, so many variables to be considered in tuning an antenna.
It sure is a lot of fine building and learning about it though.
