For quite a while I have been shooting almost exclusively with the 100-400mm lens while photographing aircraft. Recently, I knew I had a couple of smaller aircraft inbound and I picked up the 500mm which hadn’t got a lot of use for a while. While it is a fixed focal length and therefore inflexible for things getting too close, with something small, it works out fine. When I checked out the images later, I noticed that I had a far higher keeper rate at low shutter speeds than I have got recently with the 100-400.
I decided to stick with it again on another day of shooting and had similar results. I decided even to sacrifice the closer shots and work with the long lens to get framing I wanted further away and to then go for close ups of details when things got too large. I was overall very happy with the results. I think the weight of the 500mm is such that it is a lot harder to disturb it with small twitches. The 100-400 is so much lighter, maybe it is more sensitive to my lack of smoothness. The inertia of the big lens is a benefit. I think I shall be using it more again going forward. Besides, it is so sharp when you get it right!