Unfortunately, idiomatically it seems to be used more in terms of "how often are snapshots taken". But these two quantities aren't the same thing. It might take ten minutes to replicate all your hourly snapshots. Is an RPO of 60 minutes being met? Technically no, because the last replicated data could be 70 minutes old.
So if we provide an option that says "replicate this set of VMs, with a 60 minute RPO" should we just take hourly snapshots? Would it be more or less confusing to take snapshots slightly more often in order to get them replicated within the 60-minute window?