Luxury glamping competes on nightly rate rather than volume. A hut at £220 a night and a hut at £120 a night are often physically similar, and what separates them in a guest's mind is almost entirely the photography. If the first frame does not carry the price, the listing is filtered out before the description is read.
There is also a platform argument. Owners typically sell across their own direct booking site, Airbnb, and a curated listing platform such as Canopy & Stars or Host Unusual, each with different crops and different editorial expectations. A set built with all of them in mind, including deliberate portrait frames, avoids the compromises that come from cropping landscape images months later.
If your site is new, the best window is the week the styling is finished and before the first guest arrives. Everything is pristine, nothing needs working around, and you launch with a complete set rather than adding images as you go. That window does not come back once you are trading.