This from DTG about people who think Steam has remove their TSC files.

[TheKman]

Well just to be clear I am online all of the time and I have never never had Steam erase or change one of my mods as long as there is a .ap file. Remember some of the older stuff didn't have a .ap so Steam may then change your mod on items bought through Steam.

More than likely on those that have gone bye-bye on me probably didn't have the AP. I'm now aware if the what can happen if the AP is not in the folder. I added the AP back to folders that didn't have one (only 8) so I should be OK now. I'll still stay offline whenever possible.

[AmericanSteam]

I'm of the same mind as TheKman. I back up my Railworks every few weeks. I keep 3 backups then replace on a FIFO schedule. I haven't noticed any thing missing.

[kris120]

I think checking all assets has nothing to do with ap-files only.
When you let your assets check by steam all files are checked for their presence in the actual installation (I think this is obvious).

When you buy a new package at steam only this package is downloaded and checked after installation.
When there are requirements these requirements are checked, too ( I think it is like this, I could not observe this ).
But never ever has then been checked the whole installation for correctness until last winter !!!

My experience last December:
I needed to reinstall "BR Stanier Jubilee Class Loco Add-On" (RSC\JubileePack01\).
This is an old pack without ap-files, only single files and without DRM.
I have had this unchecked since years as I wanted to avoid that steam checks it when it supposes to reload my whole installation (I always wanted to minimize that).
To get the files from steam I have deleted RSC\JubileePack01\ and checked "BR Stanier Jubilee Class Loco Add-On".
I do not know whether there are some dependencies for that pack, I can only imagine there may be some with old Kuju\Railsimulator\.
But steam checked then everything and reloaded everything. I nearby have everything available !
Luckily all my mods were moved outside of Railworks at that time, but waiting 5 hours just because of the installation of one package is unacceptable.

Unfortunately I do not remeber what happened last sale around christmas when I have bought some packages.
I think I moved the original files into Railworks from the bulk download two weeks before and therefore all went well.
But on rail-sim.de several people got that complete redownload from steam after they have bought something new.

Last week I have bought a package simply as it was really cheap. Everything went well, even that I had all my mods in my UK-installation (only UK-assets).

So I think that was a big bug by steam which is fixed now (hopefully).

Kris