I have been reading the following article: https://coinmetrics.io/difficulty-estimating-chain-transaction-volume/
It mainly discusses how unreliable transaction volume on a UTXO blockchain such as Bicoin is due to factors like change outputs, exchanges making transactions and coin mixing.
My question is related to change outputs in particular. If one sends someone a 5 BTC output, from a 20 BTC input they would receive, there would be a 15 BTC change return to the address of the sender.
So what I ask is, for transactions with more than one output, can we assume that one of the outputs is always change? Wallets would not construct transactions where they split the change to multiple addresses of the sender, would they? Is the only concern then, whether the output is indeed change or it is value that is being sent over to another recipient?