Based on my own experience both target (competition) and hunting
with double rifles as well as watching people, the speed of reloading
a double is directly proportional to how much someone has practised.

A good friend of mine is very fast loading his Extractor double solely
from practice. I also find that I can load an extractor gun nearly as fast
as an Ejector gun.

Other factors that come into play are where your ammo is located
, what round it is, whether the gun has a hidden third bite or a big
lump of metal between the barrels.

Just my HO.

500 Nitro