Active LSP/FAS/VLX/DCL around 2000, of which around 200 are loaded/autoloaded into ACad, backup around 30000 (nearly 20 years worth). That might be a better question: how many are set to be loaded on a constant basis, how many are simply available for if-and-when needed, and how many in your archive? And then also how many of those are duplicates and/or different versions?
These days though I'm not doing a lot of CADing - more BIMing so my DLL's lib is starting to grow (together with their csproj source files). Around 250 at the moment (mostly trivial stuff), though perhaps only 10 of them are auto-loaded in Revit.