True single stack will ensure fewer fees. However, when you start trading your bitcoin for goods. There is a higher chance that your spending habits will be picked up and lead to a physical attack (ie every month you get groceries)

If you have one stack it looks like one stack on the blockchain. An example: if a hacker is going after a stack they would rather win .1 ₿ than .01 because it theoretically costs the same to attack the wallet. Therefore if you have multiple utxos they don’t stand out as a single target.

Ps i am a pleb without a cold wallet still learning as this on the fly