The randomness of freight stock is no surprise.
Don Rowland's work from the 1970s came to the conclusion that a layout to represent a location on the L.M.S. in 1938 with a loco shed having a ten loco allocation would require 23 coaches, 8 NPCCs and 733 wagons!
Out of that 733 some 328 would be private owner and 12 private owner specialist traffic wagons such as salt, tar, petroleum and acid.
If the layout was a half mile of double track (one mile of track) then the location could require as much as a further mile of track for sidings.
Coal was king and covered vans were only 1 in 6 of railway owned wagons (1 in 10 of all wagons).
Fitted stock amounted to only around 1 in 10 wagons.
Specialist railway owned wagons at the location would amount to 19 wagons, 13 of which would be for loco coal, sand and ash.
Back in the 1970s not even a large club would have had 733 wagons but the Trainz modeller of 2020 can put together a lot. Putting 328 PO wagons together might be a challenge though, since those 328 likely had many, many different companies represented. Probably not 328 different companies but perhaps 250. The common user agreement would mean that only around 43% of the railway owned wagons at the notionally L.M.S. location would have been L.M.S. stock. There would have been L.N.E.R. G.W.R. and S.R. wagons among the 57% which were not L.M.S. stock. Peter Tatlow admits that his lifelong interest in wagons was sparked by trying to answer the question he put to himself as a child, "why are there so many L.N.E.R. wagons at my L.M.S. home?"