Getting back to some of the questions about how much it's worth it, depending on a variety of factors, here are just a few thoughts--
Using them only occasionally because you're in a place where there aren't many of them will of course only "speed up" your journey by a small amount. But there's no harm in using them this way. To me, leaving the "jet cone boost" option turned on is worth it all the time, because then they become a fun little surprise in such places.
If you're specifically planning to cover a large distance in places where the neutron layers are reliably stocked, I find that the overall travel speed is roughly 3x that of normal jumping, (ignoring how much more or less scanning time you might include, so just comparing the straight travel time). It quadruples your jump range for those jumps, but they take slightly longer because of the supercharging, and extended refueling between batches.
It's more "hands on". This is great for me as a VR player since I can't easily do other things while playing, but it certainly could be a problem if you're trying to do chores or write emails or something alongside the game.
The time it takes to go "up" or "down" to the neutron layers has to be factored in. If your destination is close to the center plane, and only 3 kly away, it's probably not worth it. 6+ kly, and off the plane a bit, might be more viable. Larger distances are almost always faster to take the neutron highway. That upward/downward jaunt can be angled a bit, bit it can start cutting into your neutron-jumping speed bonus if you go too far off from vertical. 30-degrees from vertical makes for a pretty good path.
If you use spansh, yeah, you'll be having to copy/paste system names a lot, and none of those neutron stars will be undiscovered of course. The in-game plotter does a pretty good job, but you have to help it by getting into the neutron layers first, of course. Sometimes it will do a better job if you turn off some common classes of stars, such as M, and maybe K, depending on star density.
High jump ranges make for more optimal neutron boosting, since it has a larger number of neutron stars to choose from within your jump-range sphere. And larger fuel tanks can make for more optimal travel speed too, since you don't have to hit a refueling star as often. For these reasons, Anacondas with stock fuel tanks will typically get only 2-3 neutrons in sucsession before refueling stops, and Asps/Phantoms will get more like 4-5, and sometimes 6. This closes the jump range gap a little bit, and so Asps and Phantoms can get around almost as quickly, but not quite. It also means that even the Beluga does OK, since while it's range is shorter, it has a huge tank and can do maybe 9 boosted jumps at a time.