Mostly professional time on corporate records: reconstructing share histories, obtaining registers and drafting the ownership analysis. Government filing charges are published in the USCIS fee schedule and are separate from this work.
Corporate archaeology is the line item
Hypothetical example: two Hampton siblings expect the cost of a transfer petition to be a filing fee plus a lawyer's letter. The affiliate claim changes that, because the evidence is corporate rather than narrative. Someone has to retrieve share registers for two companies in two jurisdictions, reconstruct any transfers since incorporation, obtain the shareholders' agreement, confirm the voting position of each class and set it out in a form an officer can check. For companies whose records have been kept casually, that is the bulk of the spend and the bulk of the elapsed time. Government charges should be read from the current fee schedule when filing, and optional faster adjudication is a separate election that speeds the decision without improving the evidence.
Retrieving payroll from a retired system, obtaining certified copies of transaction documents, translating agreements executed abroad, and having counsel read the corporate chain all take chargeable time that a straightforward internal move would not require.