Where should drip-zone filtration and pressure regulation land in the quote?

For a multi-zone drip system, should filtration and pressure regulation be priced as shared system components, or separately for each zone? I’d expect the answer to depend on how the zones are laid out and what each one serves, but it’s hard to compare bids if one groups those parts together and another folds them into the zone price.

When requesting a quote, would you ask for tubing and emitters to be broken out separately from filters, regulators, valves, and controller work? I’m also curious how contractors account for flushing access and routine maintenance in the design. How many zones and what kinds of planting areas are useful to describe before asking for comparable bids?