The percentage is not the deal. The base it is applied to is the deal.
Recorded-music deals get sold as names: distribution, , JV, , "a proper ". Treat the names as positions on a spectrum instead. At one end sits pure distribution: the artist owns the , funds and the marketing, makes every decision, and pays a company a flat fee or a small percentage simply to deliver the records to the DSPs and collect the money. At the other end sits the traditional royalty deal: owns the masters, funds everything, makes the calls, and pays the artist a , with the advance and most costs before a penny flows.
Every other shape lives in between, and three variables move together as you slide along it: who funds the work, who owns the result, and who decides how the money is spent. The more the company funds, the more it owns or controls, and the bigger its cut.
For an adviser checking a statement there's a fourth variable, and it's the one that decides whether the statement can be checked at all: what the company's cut is taken from. A distribution fee comes off gross receipts. A label-services fee comes off receipts, with the company's fronted marketing then recouped from the artist's share. A profit share pays the artist a percentage of a defined net-profit pool, and that pool only exists after every cost the contract permits has been deducted. Same gross, three different bases, three very different nets.
So the first question on any statement is never whether the arithmetic adds up. It is: what is this percentage a percentage of?