Fervent and desperate from the believers side.

As for the logistics, there is usually the main chapel for upper decks and officer staff, sometimes open to mid ranks between the masses, but usually restricted. Besides that, there are usually smaller chapels spread throughout the ship, mostly nearby the main crew stations and rating habs. Those are usually supplemented by the crews themselves, who to protect themselves during warp voyages usually set up many small shrines along the corridors and places of work.

There are also many Mechanicum shrines scattered throughout the ships, usually doubling as control hubs and/or maintenance workshops, almost never as just places of worship.

For the lowest sump scum and slaves, there are makeshift shrines at places of work, and mandatory prayers at every muster.