@os79
Stack attack does not fire up the archer bombard code or range bombard code every attack sequence any more. The actual attack sequence that plays out I think is dependent on a number of things but is essentially standard behaviour. Suggest that if you have a big stack, you semi-automate the attack by selecting the catagory of units you want to attack with, and stack attacking with each category. If you have five catapults, you could stack attack with them first for example.
As for attack support, that fires up the archer bombardment and range bombard code, every time there is a single attack. If there is a two swordsmen, an archer and a trebuchet, if a swordsman attacks first, his archer will archer bombard support him and his trebuchet will range bombard support him. This will repeat for the second swordsman as well.
This mechanism was once fully integrated with stack attack, but not only made stack attack prone to CTD, but also meant that stack attack could not be used in more conventional ways, nor with the better bts AI. However if players do want the old stack attack behaviour, they just have to enable both attack support and stack attack.
Cheers.