Warrior Ancient and Medieval Rules

Scott and/or Jon:

I incorrectly posted this question under some other branch, so I will
ask it again here. I have some ideas about changes to a list, but I
want to ask a more general question up front.

The basic question is this: how many times does an army have to use
something (like equipment) or do something in order for whatever is
being done to be incorporated into a list?

For example, if an army uses artillery during a siege, would this
justify the inclusion of artillery in the army list? Or does there need
to be some open battlefield-like use of the artillery?

As another example, if an army used boats during a siege, would this
justify the inclusion of boats in the army list?

Thanks for your response.

-- Charles