A filing is a stack
Rarely does a US filing want a single certificate. It wants a birth record, a marriage entry, a qualification, sometimes a police record, and it wants them to agree with one another. Treating that as one job rather than five is the difference between a set that reads as one file and five documents that happen to share an envelope.
One spelling of every name
Names of towns, schools, courts and issuing offices rarely have a single settled English form. Left to several hands they come out several ways, and each variation is a question a reviewer may raise. Fixed once and repeated across the stack, they stop being an issue at all. That consistency is the main practical gain from assembling everything at the same time.
One date on the signed sheet
The statement of accuracy carries a date, and a clerk reading a stack will see whether those dates match. A set signed on a single day looks like what it is: one piece of work covering one bundle. Sheets added weeks later carry their own dates and invite a question about what changed in between, which is a conversation nobody needs.
Rate, days and the clean copy
The price is £25 for each side of paper as issued, so a thick stack is arithmetic rather than a negotiation. Standard work runs 2–3 business days from a complete scan and express closes it in 24 hours. Where a sheet is a birth, marriage or death entry, Derby Register Office at Riverside Chambers, Full Street, Derby DE1 3AF issues fresh certified copies to start from.