still can't confidently explain when to reach for a message queue versus just calling the service directly

Can draw the boxes fine, load balancer, cache, database, all in the right order. The second someone asks why I'd add a queue between two services instead of a direct call I start hedging with 'it depends' and hope they move on. Read the explanations, they make sense in the moment, then evaporate by the next mock. Anyone have the version that actually stuck for them?