I get the feeling everyone was there for the big meeting, not because the Fleet stayed there. The Alliance Fleet wasn't around Hoth years later for the reason that the Alliance can afford to lose either the High Command, or the Fleet, but not both.
Yeah, according to the novelization it was a big deal (and a security nightmare) having the whole Alliance council in one place. Remember, most of these people are Imperial Senators so ducking the ISB without arousing suspicion *and* getting them all to Yavin without blowing it's location is no small thing.
So that indeed may be the only reason for at least Raddus's ship to be in orbit and presumably the Tantive IV (& III?) were only there because Bail & Leia were there. Plus of course we have no idea if all the
All that said, the novelization also mentions that the Tantive IV had been docked with the '
Profundity' for repairs for some time, which one would think supports the notion that that ship at least is stationed there long-term and where the flagship goes, the fleet usually follows.
Another possible thing to take into account is in the 'Princess Leia' comic, Akbar shows up after the battle and says all the Alliance fleets (plural!) will assist in the evacuation. Just the fact that Akbar was elsewhere for the events at Scarif suggest that the Alliance had other fleets and that what we saw in Rogue One was just the Yavin fleet. The recent SWR trailer just so happens to feature a shot of what's probably
'Home One' with the fleet as early as 2 years prior to RO/ANH, so that seems to track.
They did attack the Death Star with 30 fighters and a YT-1300 freighter. Or is that spoilers for the sequel?
Well technically it was just 30 fighters. The YT-1300 turned up later of it's own accord.
Red group had 11 or 12 fighters at Yavin. Gold had it seemed to be four to six fighters present. So who were the other squadrons? Likelihood it was Green Squadron with some survivors of Blue Squadron that didn't go down to the surface. Through from what we saw, only three fighters survived that battle, with the identity of the Y-wing pilot appears to be one Evaan Verlaine (Gold Three). As far as I can tell we didn't see her in person at Scarif but her fighter was seen attacking with the rest of Gold Group against the Shield Gate and the Star Destroyer.
I've actually counted this before and that panning shot of the fighters passing Yavin does indeed have a total of 30 ships. 22 X-Wings and 8 Y-Wings.
Now strictly speaking, in real world aviation a fighter squadron can have between 12 and 24 craft, so on that front it's not unreasonable to presume that all 22 X-Wings are red squadron. That said, the highest numbered callsign mentioned is "Red 11" (Red 12 is mentioned in the script IIRC), so it's still possible those other 10 or 11 X-Wings are in a third squadron.
Another possibility is that there wasn't a pilot experienced enough to lead the survivors of Blue Squadron so they were absorbed into Red Squardon, who were also down several pilots (like red 5!
)
It's worth keeping in mind that we mostly only saw the battle from Luke's perspective, so there's a lot that we didn't see--like what happened to those other four Y-Wings for example--so just because we never saw or heard about "Red 22", doesn't mean they weren't there.
