I think this is what @vtsykun was trying to accomplish with #49806. FreeBSD has a -jitter option that does the same thing so I think there's precedent. From the (https://man.freebsd.org/cgi/man.cgi?cron):

-j jitter
Enable time jitter. Prior to executing commands, cron will sleep
a random number of seconds in the range from 0 to jitter. This
will not affect superuser jobs (see -J). A value for jitter must
be between 0 and 60 inclusive. Default is 0, which effectively
disables time jitter.
This option can help to smooth down system load spikes during mo-
ments when a lot of jobs are likely to start at once, e.g., at
the beginning of the first minute of each hour.

Usage:

// defaults to 0-60 seconds
$schedule->add(RecurringMessage::cron('@daily', $message1)->withJitter());

// customize the max seconds (0-30)
$schedule->add(RecurringMessage::cron('@daily', $message1)->withJitter(30));