Many thanks, Gareth, for your considered and thoughtful reply to my earlier rant. However I'm not wholly convinced. A couple of points:
First, that record companies survive doesn't imply they always plan their marketing strategies (I did in my youth teach logic!). True, there is considerable evidence of careful thought and planning on the part of people like Hyperion - in their early days they battled against the then dominant major labels precisely by such planning. At the other end of the spectrum there are those lumbering majors whose output seems to me to be largely determined by what conductors or soloists on their lucrative contracts want to record, which is often not the same as what the market needs. Hence endless packages of Beethoven or Brahms or Bruckner...and even yet another complete Ring cycle in the offing. The good thing I suppose is that if companies are faced with even more severe economic difficulty then they will be forced to plan releases with the utmost care, or just fizzle out. On second thoughts, maybe not: borrowing a Darwinian idea, they will survive by diversifying. And that will doubtless mean, and I groan, much larking about with more sophisticated technology and trying to grab the interest of the gullible and those too afraid of listening to music fully. (Lots of prejudice here, for which I make no apology!)
Next, the 'sound musical reasons'. Yes, Gal and Schubert are certainly kindred spirits. But that is surely no reason to put them side by side on the same CD, when (to repeat my earlier point) the 'space' taken up by Schubert could have been used to give us the second of the Gal symphonies. I'm sure that one disc containing Gal 1 and 2 (and then presumably a second later CD giving us 3 and 4) would get Gal a wider audience than would be the case by scattering his symphonies amongst those of Schubert, Schumann or other kindred spirits. Bach and Reger are distant kindred spirits - but maybe it would be poor marketing strategy to squeeze both on the same CD (though of course a judicious selection of material might be musically interesting).
Finally you can't seek a justification of Avie's decision to offer joint Gal and Schubert discs by pointing out that you don't happen to have a recording of Schubert 6 and 9, and that this will be a useful way of acquiring them. First, I suspect you're in a pretty small minority in being, as it were, Schubertless. I would guess most people contemplating buying a CD of Gal would already have Schubert on their shelves, and that might well incline them not to buy the CDs. And second, if you want (as you should!!) to add Schubert then, with all respect to the Northern Sinfonia and Thomas Zehetmair, there are probably easier (and less expensive) ways of doing so.
So maybe, in friendly fashion, we should agree to disagree! And let us instead turn the ear to music, for that is an infinitely more pleasant activity than squabbling over marketing strategies!