It's not unusual for a workshop item to contain multiple assets. Sometimes you will find a bunch of similar props, which are bundled into one item on the workshop. Sometimes it can be buildings packed together. The Loading Screen Mod counts everything that's loaded, so every item in a pack, while the workshop just lists your subscriptions to workshop items, not caring what's inside those. :)As an exampel this is 4 buildings packed in one workshop item.
https://steamcommunity.com/sharedfiles/filedetails/?id=2075191304

Originally posted by xerxesaria: So if I understand correctly:

I have:
50 maps, themes, LUTs
800 assets (buildings, vehicles)
Total: 850 subscribed items

But in reality, as LSM shows, I have:
1300 "ITEMS", which are contained in all of my DOWNLOADED materials, which include maps, themes, buildings, vehicles, etc.

So when they advise that you should try to minimize your "ASSET" count to around 800 to speed up load time and run the game smoothly, do they have it about the number that shows in LSM (i.e. 1300) or the number that shows in subscription count?

LSM shows just assets, so buildings, props, vehicles, trees, citizens, roads etc. So the number it shows, is the number that recommendations are for. Since Steam subscriptions can contain multiple assets, there isn't much point in counting those and making recommendations on them.