Shipping Sort Order

I have a question on shipping sort order. I am on OC 1.4.9.6
I use 3 types of shipping extensions.

A) Free Shipping for specific items when order total is over $100, Item_ZZ, Item_KK, Item_JJ
B) Flat Rate Shipping for some specific items Item_A, Item_B, Item_C
C) Everything else is Weight based shipping, Item_F, Item_N, Item_Q

This may be a simple question. In what order would it make the most sense to have the evaluantion
proceed? A as 1, B as 2, and then C as 3?

Right now I have it as B as 1, C as 2, and A as 3. But I see some situations where if you have all 3 types in the
same cart the shipping is technically not calculated correctly. What would be the best advice? or the best
way of looking at this in situations where all 3 items could exist in the same cart?

Shipping methods in OpenCart are independent of one another, so changing the settings of one will not affect another. This also means shipping costs cannot be combined -- each shipping method that is enabled will be presented to the customer as its own option.

If you need combined shipping costs for different items, you'll need to set it up within a single shipping method. My Product-Based Shipping extension can do this, or if your items are divided into discrete categories, Category-Based Shipping works the same way.