Should I expect the delays I specify in an MH Journey to work punctually?

Should I expect the delays I specify in an MH Journey to work punctually?

I've set a one hour delay in a Journey. I can see that a contact entered the Journey at 1001 (screen-119) but, that screenshot also shows, it's now 1120. The 1-hour delay has long since passed and the second step of the Journey hasn;t been executed. I'm wondering if this is just slow or whether there's a different problem.