For example, I grouped nearly all the non-philatelic Trident covers and cards into a few large Lots. This is what they looked like:
Podillia over 250 items [Lot 115 Start 5000 Swiss francs Hammer 12500]
Kyiv over 175 items [Lot 74 Start 4000 Hammer 6500]
Odesa over 90 items [Lot 104 Start 3000 Hammer 4400] (the Trachtenberg covers went into a separate Lot 107 Start 900 Hammer 1900)
Katerynoslav over 60 items with no ENAKIEVO EKAT stuff [Lot 93 Start 3000 Hammer 4400]
Kharkiv over 40 items [Lot 86 Start 2000 Hammer 2600] I bought this Lot
Poltava over 40 items [Lot 99 Start 1500 Hammer 3400]
My guess is that this ordering tells us something about the relative volume of mail in the different Districts during the period of Ukrainian independence. If anything, I would expect Podillia's lead to be greater than shown here. That is because the Zelonka collection did not appear to include much from the enormous Vyrovyj collection which was auctioned after Dr Seichter's death and therefore not incorporated in any way into Seichter's collection - which formed a large part of Ron Zelonka's postal history holding.
Kyiv includes uses in Chernihiv and Zhitomir postal districts - their own issues are scarce othe than philatelically used.
Just 40 items from Kharkiv seems small in relation to the size of the city but it was an area of intense conflict and early Sovietisation.
Of course, all these Lots showed stamps used outside of their District of issue. Indeed, it is sometimes remarkable to observe just how much movement of stamps between Districts there was and a study could be made of out-of-district uses. For Podillia, for example, you can find the issues of Kyiv, Odesa and Kharkiv. I think I have even seen Poltava used non-philatelically in Podillia.