I'm bucking the trend with a 64t tank
I have a test run of exactly 1000LY - Founders World to M7 SECTOR LS-T D3-15
My fastest journey times for this run in an Asp with an A6 fuel scoop are:
with 16T fuel tank, and 30 jumps, 28 minutes.
with 64T fuel tank, and 35 jumps, 25 minutes.
These are both easily within the usual range of travelling about 2K LY per hour and could probably be improved slightly, as I wasnt racing too hard.
BTW I never start the next FSD above 60% heat, which is usually the point the scoop disengages anyway.
But why is a big tank faster, even though it has more jumps ?
Basically, as other people have noted, it's because it takes significant time to get the fuel scoop up to full rate. If you scoop often into a small tank, you hardly ever get the scoop up to max. People have used this as a reason for going with smaller scoops, but that isn't the whole story.
With a 64t tank, I only had one concerted scoop up to full, which took over a minute, but that was consistently at the max rate. Scoops also occur incidentally whilst turning to face the next jump target, and these act as top-ups.
This also occurs with a small tank, of course, but your primary concern there is often scooping, not turning.
With a large tank your immediate priority is to turn to the next target star, without having to worry about, or check, whether it scoopable or not. This reduces the job to turning, scanning and waiting for the FSD to cool down, all of course at the same time.
I haven't tried the run in an anaconda because the turn rate to the next target is so slow, I gave up exploring in it long ago.
My preferred exploring method is to choose an interesting destination and get there asap. I think this will fit with Distant Worlds quite well, there wont be time for dawdling.
Of course, with 64t over a 16t tank, you will also get 16% more exploration credits simply by scanning more systems.
I would be interested in other peoples' view on this and if you decide to do the 1KLY run above to post your results.
There is a very well endowed HMCW at the far end.
PPS The above begs the question about the standard 32T tank.
Well, it takes an hour to get there and back, and in the past 3 hours I have been unable to get a clean run in.
Mostly due to hyperspace jumps taking far longer than usual - probably server slow down issues, and a couple of times where the plotter has lost the plot (!) and I had to re-enter the destination.
All these things have negated the test. However, I did get close to finishing on one occasion, and the time was on track to be about 27 minutes.
The experience is that you can totally ignore scooping when the tank is above half full, but below that you need to be aware. In total it needed 4 full scoops apart from the usual top-ups.
My conclusion is that a 32t is perfectly ok, but I prefer 64t just to simplify the turn-scan-fsd method, and I'd rather have that than either a extra FMU/cargo/extra SRV, even though I really did want to take some beer.