Beware: not all seem to run like that any more. Some of them seem to have become basically club-ride-seeding races with start waves with vague names like "espresso", "cappucino" and "latte" with different start times but each wave basically full of people trying to hammer round the course to be hailed as the "winner" of their wave on social media later in the day. As far as I can tell, submitting a GPX has replaced route card stamps, so now no stopping is required. So, I now "look out for" certain ones, but to avoid their route if possible
As ever, ask questions about a new event with a new group. If they won't answer friendly questions from a newcomer, I tend to think they're a bunch of selfish self-gratification artists I probably don't want to ride with anyway