I do SRE / Platform type of work where I'm technically on-call 24/7/365 but as a salaried worker I don't receive over time or anything like that. If an on-call event happens where I end up putting in 2 hours on a Saturday or Thursday night, I'd use my discretion to leave early or start late another day.
In the roles where on-call was an expectation, it was focused to critical downtime events, not to answer a Slack message from someone working in a different time zone or non-standard schedule. I don't even have work Slack or email on my personal phone. If PagerDuty goes off from a critical alert I get called, that's the only way I get contacted outside of normal hours.