Depends on the image and the gear.
I will use my Canon 600/4 IS II for birding on my action gear, but I would never use that lens on my landscape gear (which is equipped with either a Rodenstock or a Schneider Kreuznach lens).
Although I have a range of zoom lenses from 16 to 400mm, I tend to gravitate towards fixed focal length.
Depends on the image and the gear.
I will use my Canon 600/4 IS II for birding on my action gear, but I would never use that lens on my landscape gear (which is equipped with either a Rodenstock or a Schneider Kreuznach lens).
Although I have a range of zoom lenses from 16 to 400mm, I tend to gravitate towards fixed focal length.