Local conditions
New estates have no eaves worth the name
The Wall Gets Hot Before The Window Does
Older Queensland houses were built with deep verandahs because there was no other way to keep them liveable. A lot of what has gone up since has eaves you could measure in centimetres, and shading has to be sized for the sun angle you actually get — which, on a western wall here, is low, long and straight through the glass from about three in the afternoon.
An awning is the only thing that fixes that from outside the glass, and outside matters. Stopping the heat before it reaches the window is worth far more than stopping it after, which is why an awning will outperform any internal blind on the same opening on the same afternoon.
The catch is wind. Brisbane and the Gold Coast both get sudden summer southerlies, and a folding arm awning left out in one is a large sail on a small bracket. Retract it, or specify a fixed awning and accept the smaller span. We would rather have that conversation at the quote than after.