How much margin do you normally keep when sizing a flow meter for an oil & gas application?

I'm working through a metering datasheet where the expected flow is around 10,000 bbl/day, with roughly 50% turndown.

For the datasheet, would you normally consider:

• Minimum: 5,000 bbl/day
• Normal: 10,000 bbl/day
• Maximum: 10,000 bbl/day + some engineering margin?

I'm more interested in how people handle this in actual projects, especially when turndown and meter accuracy are both important.