Serious claims are built around evidence, and the evidence takes time. Medical experts in the relevant specialties assess the injury and give a prognosis, which means their view on how it is likely to develop. Where care, equipment or housing needs are in issue, further experts assess what is reasonably required and what it will cost.
The reports are often obtained in stages. An initial report establishes the nature of the injury. A later report updates it once the condition has stabilised, which may be a year or more afterwards. Where the injury is still changing, settling on the strength of the first report alone would risk under-compensating for problems that had not yet emerged.
Alongside the medical and care evidence, the financial losses have to be proved. That may mean obtaining payslips, accounts, pension records and benefit information, and in larger claims instructing an accountant to project what the person would have earned had the injury not happened. Only once that picture is reasonably clear can the value of the claim be advised on properly, which is why we are cautious about early figures.