Never Recycle a Building: Rather subverted – inasmuch as while the Imperials don’t tend to go around demolishing perfectly good buildings they don’t have a current use for –
(Leading to the related phenomena in which some buildings have been in continuous use and upgrading for something like seven thousand years along with all their different schools of architecture.)
Since that would be all wasteful and entropic, it would be every bit as bad to just abandon them and let them decay untouched. So you’re very unlikely to find an actual accessible abandoned building, even very shortly after it’s notional abandonment: what you’ll find is one that has been carefully stripped down, wrapped up, secure-sealed, and prepared for long-term “storage” by a professional mothballing crew.
So, sure, that decades-old abandoned building will be perfectly intact and everything in it will probably work, if you want to go to the trouble of unsealing and de-mothballing it…
…but if you left stuff behind there, it’s likely to have been cleaned up, sorted, sealed into crates, filled with inert gas, and shipped off to last-known-address postage-due, or failing that, the Bureau of Unattached Chattels and Uncertain Titles.