We take 20 minutes for a disembark, 800 lit refuel, embark, bags etc. on a crew change for a 92 or 225. It is a bit helideck crew dependent.
We schedule 30 mins between aircraft departures from base so as one lifts offshore the next is 5-10 mins out when we do cyclone evacuations of a MODU.
Gap between landings dependent on wake turbulence but wind in the NS dissipates it within 30 seconds or so. However, in reality, the likelihood of having aircraft queued up one behind the other is low.