But the more central sectors probably don't have very many subsectors that aren't duchies. My guess is that the Marches are pretty extreme in this respect. The figure I usually calculate with (and it's a complete guess) is that 10% of the subsectors with regular fleets are not duchies. Until someone actually sits down and figure out the structure of all 300-odd subsectors, that's probably the nearest we can get to it.I'm not sure you can carry the analogy too far. The Marches, for example, appear to only have six duchies but eleven subsectors, in Imperial space. Which might be why MT switched to subsectors?
The MT system is different from the CT system. A genuine, deliberate retcon. I advocate re-introducing the duchy fleets because I think the setting would be more fun that way, but I'll be the first to admit that you can't use the evidence from MT concerning the reserve fleets to tell us anything about the subsector navies from CT.Further, the MT system shows separate numbered fleets in EVERY subsector, and further, many have 2 numbered fleets, a few have 3. And each has a matching Numbered Reserve Fleet.
Not that I think it would be necessary to completely do away with the reserve fleets even if the duchy navies were reintroduced. In fact, I think they'd fit in very neatly.
Instead of either having:
1 Imperial Navy (Sector level and up)
2 Subsector navies (subsector level)
3 Planetary navies (member worlds)
or:
1 Imperial Navy - regular fleets (Sector level and up)
2 Imperial Navy - reserve fleets (subsector level)
3 Planetary navies (member worlds)
I suggest:
1 Imperial Navy
....1a Regular fleets (sector+)
....1b Reserve fleets (subsector)
2 Duchy navies (duchy)
3 Planetary navies (member worlds)
It doesn't even have to contradict the MT information (well, not much anyway

Hans