Small startup, tech team of about 10 (2 SREs + 7 devs + 1 biz, total company size is 20, fully remote distributed across 3 continents), roughly 8 hours twice a week and only during my local timezone business hours, then the same 8 hours in one weekend day every two weeks, also roughly. We have lots of automated checks and alerts and only react to critical ones paging us via Slack (most of the alerts that page us are known, some are flaky some are false positives we can't ignore).
It was kind of forced on everybody (prematurely IMHO) but respecting people's timezones and business hours was key to make it acceptable and you can take the next day off no-questions-asked if you were on call on a weekend day even if you didn't have to act on anything. It's far from ideal considering how we still react to the critical alerts and what in them usually triggers actual on-call support but I've had worse in the past so it's alright... for now.