I think it was "Caretaker" where they said they had a 5 year supply of deuterium. They probably used it a bit faster than expected so needed more in "Demon", but then had enough for the rest of the journey.
The big problem I have with them running out of deuterium is that
this is one of the few things they should have had no trouble acquiring. That's what the Bussard collectors are literally for, and hydrogen accounts for 73% of all (normal) matter! Admittedly deuterium is a rarer isotope of hydrogen, but it still accounts for ~0.011% of all matter in the universe – which still makes it more common than oxygen.
My headcanon is that the "solar dive"
Voyager does in the title sequence, where it flies beneath a solar flare, is a refueling manoeuvre.
Berman admitted that it wasn't a good idea to have two series on at the same time.
Modern
Star Trek: "hold my root beer"
Or 7 anyway. Dispense with Chakotay and Harry, or reduce them to recurring status. And also, have the recurring cast be:
* Diverse species. Instead of 140 humans and 5 "other", throw in Vulcans, Andorians, and other Federation species. Since they're only appearing occasionally, makeup shouldn't be that big an issue.
* In and out. Have some humans stay on Planet 37's, and maybe pick up new crew there. Have people you see repeatedly and actually care about die. Have new DQ crew join the ship.
I love this idea. The closest we came were the Borg children, but really that's ultimately what happened with Neelix in a way. Have recurring characters who were around for a season or two, that had useful skills they could trade for passage.
* Have the crew act like this is their life for the foreseeable future. People pair off, like Tom said they would. Janeway is seen marrying couples. Kids are born. Things get a little more casual as Voyager becomes an intergenerational vessel.
* Have a little fun with "Romances of the week". Maybe a romance occurs and a characters joins or leaves, think Lalieri in "Galaxy Quest".
It's kind of interesting that
Enterprise depicted this whole idea better with "E²" than
Voyager managed in an entire series, and it was one of the show's core concepts
The "Going Home" thing shouldn't have been a thing at first. They shouldn't have known where exactly they were relative to the Federation at all and only learn so later on, thereby justifying them staying in the same one area for the first season learning more until they know where to go. This makes it easier to justify recurring external characters and worlds.
But it would be almost trivially easy for any 24th century starship to figure out where in the galaxy they were, at least approximately, to within a thousand lightyears or so. We have the technology to do so today, based on apparent positions of things like the Milky Way's satellite dwarf galaxies, certain long-range pulsars, and high-intensity radio or X-ray sources. In TNG: "Where No One Has Gone Before" the
Enterprise-D is able to figure out which galaxy it's in quite quickly, and even
which side of that galaxy it's on, relative to home, though simple galactic triangulation, and in DS9: "Emissary" the runabouts were easily able to figure out where the gamma quadrant terminus of the Bajoran wormhole was within moments of arrival. While being
completely lost in
completely unknown and uncharted space with no idea how to get home is certainly an interesting idea, it would mean that the ship would have to be so far away from the Federation that returning home would be essentially impossible – which would fundamentally alter the premise of the show.